SAAC Forum

I searched everywhere with no results at all.

Have any of you found a source publishing tested results of '60s Ford performance intake manifolds CFM flow numbers? I can't find anything.

Head flow numbers are by comparison easy to find.

Have any of you done Extrude Hone on any of the intakes?


I seem to remember Cobra Automotive offering Extrude Hone on the Cobra high rise intakes but haven't talked to them recently about it.

I was a subscriber to Hot Rod magazine from 1970 through to the end last year. I don't recall ever seeing data on intake flow in cfm.

    Flow benching just an intake manifold alone 'might' product some interesting numbers, great for bench racing and magazine articles, but to produce something perhaps more relevant, the task is to bolt the intake to the cylinder head as flow tested and establishing the effect that the intake had on the previous cylinder head alone numbers.  ;)

    Scott.

Quote from: pbf777 on January 07, 2025, 08:05:23 PMFlow benching just an intake manifold alone 'might' product some interesting numbers, great for bench racing and magazine articles, but to produce something perhaps more relevant, the task is to bolt the intake to the cylinder head as flow tested and establishing the effect that the intake had on the previous cylinder head alone numbers.  ;)

    Scott.

Yes but it would make sense to know if the intake manifold is going to be complimentary to the head or restrictive.

It seems to me that there is much flow bench testing on intakes and talk of intakes having good runners and bad runners and descriptions of as much work done to intakes as the heads in many instances.

To me it makes as much sense to match the intake to the head as matching the cam to the head.

If I have a head that flows 300 cfm at .600 lift, I'll bet that it isn't flowing 300cfm at .480.


To suggest that the intakes are looked at as irrelevant is a bit juvenile.

I'm only asking if anyone had a link to published testing results of Ford intakes, for my own purposes. That's all.   :)


I would think that a no response would simply mean that they didn't?

Quote from: shelbydoug on January 07, 2025, 10:15:48 PM............ it would make sense to know if the intake manifold is going to be complimentary to the head or restrictive.

To me it makes as much sense to match the intake to the head as matching the cam to the head.

    Since one is generally going to be choosing an intake from a finite sum and of that which is already in the market place, not to mention most of the intakes for most of these push-rod engines are pretty much of a know quantity at this point, though perhaps not in the minutia detail, but close enough that with reasonable familiarity as to to rule out idiotic match-ups, that anything more is becoming a study and this requires a certain sum of relativity and understood comparatives.   ;)

QuoteIt seems to me that there is much flow bench testing on intakes and talk of intakes having good runners and bad runners and descriptions of as much work done to intakes as the heads in many instances.

    Yes, but beyond my previous posted statement of fodder for magazine articles, and though one "generally" (in racing) is of the impression that there should be equality among the inlet passages, but then what about each cylinder head port passage, are they balanced, do the engineering requirements even permit for this?  But do note that in certain instances once bolted to the cylinder head, providing the air columns' real-life presentation to the head, effective lengthening and added complications of the overall passage, the actual effective impact here that solely of the inlet runners might provide a somewhat different even confusing impression.   :o   

QuoteIf I have a head that flows 300 cfm at .600 lift, I'll bet that it isn't flowing 300cfm at .480.

    If what your eluding to here is attempting to decipher the intake manifolds ability to harmonize at certain air flow quantities and velocities, etc., that's going to prove a bit more involved than just acquiring air flow numbers from a bench; and pretty much relegates the average person to my first paragraph of that most intakes available are known.   ;)   

QuoteTo suggest that the intakes are looked at as irrelevant is a bit juvenile.

    I don't think anyone was implying that, but rather just attempting to aid others in a better understanding in the value of such observations.   :)

    Scott.

You can make it as complex as you want to but it is a simple fact that air flow is proportional to horse power potential. Engines are air pumps.

For normal people, we attempt to explain the formula in simple terms. It's just easier that way.


In many Masters of Engineering degree programs, presentation of data is more then just 3 credits. It includes all sorts or artsy ways to present results including colorful graphs and simple charts that even MBA's can understand.


In the case of selecting components for an engine build, logic would dictate to match the components to be complimentary and to act as a simple integrated system. Data acquired isn't always absolute but a prime indication where one likely should search.

In the case of using vintage Ford intake manifolds, although their potential is likely known to more then just one engine builder and certainly many of the day, I need to translate that into language that I can understand and apply.

Someone probably has done that but so far I don't find that info readily available so it is most likely that no one wants to bother with listing the numbers or less likely, it is just proprietary.

As far as your statement about intake flows being already a known entity, nowhere can I find a mention or even suggestion of flow by current or recent manufacturers. So leaving that process up to investigating even if just for entertainment reasons to magazine builds seems more like being complicit in instigating conspiracy theory? In other words if you're proud of your product, show us the numbers. What's the BFD?


If magazine builds want to explain why the same engine with intake manifold A makes 25hp more at a certain RPM then manifold B, and they show something that likely is relevant like differences in flow numbers, good for them. That is solid engineering.

So far, no one has come forth willing to share that info so take your pick as to the reason. I don't really care why. I just continue to search for it. Call me compulsive if you like.

Ouch. On behalf of all the MBA's out there, it was engineers that designed the Tunnel Port. LOL

Quote from: csxsfm on January 09, 2025, 09:37:33 PMOuch. On behalf of all the MBA's out there, it was engineers that designed the Tunnel Port. LOL

Yes. It works well but here's the thing, you need to know how to apply it.

It is more then just picking something off of a list.

8)

Quote from: shelbydoug on January 09, 2025, 09:07:45 PMI need to translate that into language that I can understand and apply.

If magazine builds want to explain why the same engine with intake manifold A makes 25hp more at a certain RPM then manifold B, and they show something that likely is relevant like differences in flow numbers, good for them. That is solid engineering.

     If a 'magazine' should choose to present any such statement (and they have often  ::) ), as one whom has been a participant in magazine "tech" articles, I would advise one to establish a corroboratory source before running to the bank!  ;)

     The final straw that resulted in our separation from participation in the tech articles with the "magazines" was when we were attempting to explain that the information we had supplied was not being presented accurately, nor in a fashion that provided for a proper conclusion (again!  ::) ); and it was at that point that it was explained to me that they (magazine) didn't care if the "tech" was accurate or even true, "as we're not here to educate the public, we're here to sell magazines, and we believe that the manor in which we have chosen to wright the article would sell more magazines"!  :o

     But, I suppose this thread is evidence that 'I' was wrong; as apparently a great sum of the populace really didn't want the facts, rather something easy to read and entertaining!   :-[

     Scott.

Quote from: pbf777 on January 10, 2025, 11:10:00 AM

Quote from: shelbydoug on January 09, 2025, 09:07:45 PMI need to translate that into language that I can understand and apply.

If magazine builds want to explain why the same engine with intake manifold A makes 25hp more at a certain RPM then manifold B, and they show something that likely is relevant like differences in flow numbers, good for them. That is solid engineering.

     If a 'magazine' should choose to present any such statement (and they have often  ::) ), as one whom has been a participant in magazine "tech" articles, I would advise one to establish a corroboratory source before running to the bank!  ;)

     The final straw that resulted in our separation from participation in the tech articles with the "magazines" was when we were attempting to explain that the information we had supplied was not being presented accurately, nor in a fashion that provided for a proper conclusion (again!  ::) ); and it was at that point that it was explained to me that they (magazine) didn't care if the "tech" was accurate or even true, "as we're not here to educate the public, we're here to sell magazines, and we believe that the manor in which we have chosen to wright the article would sell more magazines"!  :o

     But, I suppose this thread is evidence that 'I' was wrong; as apparently a great sum of the populace really didn't want the facts, rather something easy to read and entertaining!   :-[

     Scott.

Too large a portion of the "population" (worldwide) believes what is in ANY print, what others post on social media and some even agree with entertainers like the Marshal Tucker Band, "I heard it in a love song, can't be wrong", unfortunately.


Being an unreliable source of information just makes one a joke like the "Inquirer" is but they do have their loyal followings. Some much so that it gets used primarily as a tongue in cheek source and limited primarily to being quoted in purely fictitious situations such as feature length movies like "Men in Black".

Depending on unreliable sources should not be part of the plan. So far I have found zero sources and zero information available. While I am a bit surprised, I am not pushed over the limit to suicide. On the contrary.

In actuality, I already have a plan previously acted upon and looking at what others have published would just be investigated as supportive or non-supportive of that.


Manufacturers are not magazines. Many are currently showing their own test results in aftermarket heads. Interesting that none, even folks like Ford Racing, haven't on the intake manifolds.

Ah,favorable press helps the magazine's bottom line.

Hi,
Just thought back about a conversation with a local engine builder from years ago. He said the intake manifold was "Not as critical to port matching as time is better spent on the proper camshaft, and that it is the turbulence created inside that increases air flow and helps with power improvement." He also says that after spending hours port matching an intake it showed only 2 HP increase on the Dyno....Some science and math do apply and think of what has been learned in the aerodynamic field in the last 60 years.
If you get a chance look at a current Top Fuel engine and try to imagine power in that magnitude 10 years ago. What are you trying to get from a 1960's design???
R.R.

This information is available, open source.
This is not the forum for technical questions requiring specificity under controlled methodology.
I suggest Speed Talk or the FE Power forum (other engines) where posters such as Joe-71 (JOE-JDC) (now retired), and others such as Bill Carlquist and John Mummert have quantified the panoply of SBF single quad intakes, including baseline flows. Their interests are primarily rule-limited vintage racing and rule-limited competitions, such as Engine Masters.
Rememeber, the air begins prior to the intake and ends in the atmosphere aft of the tailpipe.
Good luck.

You can peel this hobby like an onion ..  being interested in a facet  that  may or may change "your idea" of the onion  is part of the interest that keeps the hobby going forward .  how many times can you argue what color the floor is on a 67  gt 350.
 new thoughts are welcome and needed .

if i had the flow bench  doug and i would be doing some testing  .... even if we were the only ones that cared .

I'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desirable combinations" that would fall into the "desirable vintage" combinations.


One of the subjects was what effect on HP air flow had. Within that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race ported and dangerously thin, thought to be around 220cfm.

Then we had the iron GT40. Thought to be in the 240 vicinity as cast.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock as cast C60A would show now and he thought 240. So complimentary to a GT40 head in his mind.


So we can get into what are good flow numbers are, etc., but with Curt's comments about extrude honing the "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads now, I was just looking for those done on intakes. As always for comparative reasons.

Flow numbers are key indicators of the likely horsepower potential available. They are not ultimate's. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400 usinf NHRA factor charts at the track.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. It is still a small group of numbers nerds? Very curious indeed.  :)

Quote from: shelbydoug on January 11, 2025, 02:10:25 PM

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desireable combinations" that would fall into the "desireable vintage" combinations.


One of the subjects was what effect on HP air flow had. Withing that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race pported and dangerously thin. 22cfm.

Then we had the iron GT40. Thought to be in the 240 vacinity.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock C60A would show now and he theough 240. So complimentary to a GT40 head.


So we can get into what are good flow numbers are, etc., but with Curts comments about extrude honing his "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads, I was just looking for those done on intakes.

Flow numbers are key indicators of the likely horespower potential available. They are not ultimates. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. Very curious indeed.  :)

I used to have a Superflow 600 bench. I can use per the deal of when I let it go to the new owner anytime I want. However now it is a 1,000 mile trip to where it is. I'm currently working on port matching a C6OE-A intake to a set of AFR cylinder heads for a 352" build on a Dart block. So I was pleased to see there was enough material to make the intake ports roughly a consistent 0.050" smaller all the way around.


We'll see how it goes.


John

Two observations.

I suspect that NASCAR Cup teams have been all over intake manifold flow efficiency but I doubt they would ever reveal details.

As for selling magazines, one editor who I would trust to accurately explain flow details would have been Hot Rod's late Marlan Davis. Why he never did will never be known.

Quote from: JohnSlack on January 11, 2025, 03:31:11 PM

Quote from: shelbydoug on January 11, 2025, 02:10:25 PM

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desireable combinations" that would fall into the "desireable vintage" combinations.


One of the subjects was what effect on HP air flow had. Withing that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race pported and dangerously thin. 22cfm.

Then we had the iron GT40. Thought to be in the 240 vacinity.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock C60A would show now and he theough 240. So complimentary to a GT40 head.


So we can get into what are good flow numbers are, etc., but with Curts comments about extrude honing his "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads, I was just looking for those done on intakes.

Flow numbers are key indicators of the likely horespower potential available. They are not ultimates. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. Very curious indeed.  :)

I used to have a Superflow 600 bench. I can use per the deal of when I let it go to the new owner anytime I want. However now it is a 1,000 mile trip to where it is. I'm currently working on port matching a C6OE-A intake to a set of AFR cylinder heads for a 352" build on a Dart block. So I was pleased to see there was enough material to make the intake ports roughly a consistent 0.050" smaller all the way around.


We'll see how it goes.


John

I'm a C60A-A on a 347 with AFR heads. Somehow this monster likes BC-BD Holleys better then 2 1850's? I suspect there is quite a better flow in the as cast manifold then Mr.Gillis suggested to me of 240cfm per cylinder?

Kind of difficult to take a virtually new intake and risk an Extrude Hone, especially if there is no reason to do it.

If you are talking about the wall thickness of the intake runners on the C60E-A, at .050" thick, that is my concern with touching anything but gasket matching them. In my case with my combination, as cast on the manifold and as delivery CNC ported by AFR, that is not necessary as is.

In leu of comparative flow numbers for either of those intakes (presuming the C60A-A and the C60E-A are identical) the only reasonable place to improve them seems to be in smoothing the plenum to port transitions internally. For me, best to leave the thing alone.

Quote from: shelbydoug on January 11, 2025, 07:50:38 PM

Quote from: JohnSlack on January 11, 2025, 03:31:11 PM

Quote from: shelbydoug on January 11, 2025, 02:10:25 PM

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desireable combinations" that would fall into the "desireable vintage" combinations.


One of the subjects was what effect on HP air flow had. Withing that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race pported and dangerously thin. 22cfm.

Then we had the iron GT40. Thought to be in the 240 vacinity.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock C60A would show now and he theough 240. So complimentary to a GT40 head.


So we can get into what are good flow numbers are, etc., but with Curts comments about extrude honing his "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads, I was just looking for those done on intakes.

Flow numbers are key indicators of the likely horespower potential available. They are not ultimates. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. Very curious indeed.  :)

I used to have a Superflow 600 bench. I can use per the deal of when I let it go to the new owner anytime I want. However now it is a 1,000 mile trip to where it is. I'm currently working on port matching a C6OE-A intake to a set of AFR cylinder heads for a 352" build on a Dart block. So I was pleased to see there was enough material to make the intake ports roughly a consistent 0.050" smaller all the way around.


We'll see how it goes.


John

I'm

Quote from: shelbydoug on January 11, 2025, 07:50:38 PM

Quote from: JohnSlack on January 11, 2025, 03:31:11 PM

Quote from: shelbydoug on January 11, 2025, 02:10:25 PM

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desireable combinations" that would fall into the "desireable vintage" combinations.


One of the subjects was what effect on HP air flow had. Withing that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race pported and dangerously thin. 22cfm.

Then we had the iron GT40. Thought to be in the 240 vacinity.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock C60A would show now and he theough 240. So complimentary to a GT40 head.


So we can get into what are good flow numbers are, etc., but with Curts comments about extrude honing his "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads, I was just looking for those done on intakes.

Flow numbers are key indicators of the likely horespower potential available. They are not ultimates. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. Very curious indeed.  :)

I used to have a Superflow 600 bench. I can use per the deal of when I let it go to the new owner anytime I want. However now it is a 1,000 mile trip to where it is. I'm currently working on port matching a C6OE-A intake to a set of AFR cylinder heads for a 352" build on a Dart block. So I was pleased to see there was enough material to make the intake ports roughly a consistent 0.050" smaller all the way around.


We'll see how it goes.


John

I'm a C60A-A on a 347 with AFR heads. Somehow this monster likes BC-BD Holleys better then 2 1850's? I suspect there is quite a better flow then Mr.Gillis suggested?

Kind of difficult to take a virtually new intake and risk an Extrude Hone, especially if there is no reason to do it.

Quote from: shelbydoug on January 11, 2025, 07:50:38 PM

Quote from: JohnSlack on January 11, 2025, 03:31:11 PM

Quote from: shelbydoug on January 11, 2025, 02:10:25 PM

Quote from: JohnSlack on January 11, 2025, 11:29:40 AMI'm fairly certain from my conversations with Larry Ofria when I worked for him that Valley Head Service flowed the cylinder head intake manifold combination for the C6OE-A dual quad manifolds. Not necessarily for the numbers as to how well they were flowing but to make sure that they actually got the flow improvement that Shelby was paying for.

Later on in my conversations with Dan Case regarding the C6OA-E T/A intake he seemed to think that Mondello's head intake combination for the T/A intake was flowing better than the VHS combination.

The intakes were available in limited numbers to the Shelby people, definitely not available for Bud Moore's LM Cougar cars. The intakes provided to Shelby privateers were not modified by either VHS, Mondello, Charlie Slover or Ken Sperling. But out of the box.

I think that some of the numbers you are looking for are based on conjecture as the flow benches were not consistent with each other. Larry's VHS flow bench took up a whole room and was a magnificent piece of equipment. I never saw Mondello's or Ken Sperling's flow benches I saw Charlie Slover's bench but I doubt that the machines were as consistent as a modern flow bench mass produced. Even the modern flow benches have to be calibrated to get consistent numbers. For in house usage back in the day you could see on a port to port basis if the work you accomplished was a good result or not. However if you wanted to compare the intake manifold from this group to that group you would have had to choose one bench to use.


So even if you found the information you desire it would be junk compared to what you you could achieve today.


John

I appreciate the input.

In a recent/distant conversation with Curt Voght, in regards to the 620hp 292 "vintage" engines he was building, he mentioned that he was using the Blue Thunder Cobra high rise and extrude honing them.

A single 4v intake is a different animal, particularly when compared to the C60A.


The C60A in and of itself, is rather unique. It is a large port manifold, with equal length runners. The "tunnel ran" intakes were not yet in existance, but this manifold has some of the qualities of what would come to be common in tunnel rams.

In private discussions with "Randy", who was instrumental in me obtaining mine, we were discussing "desireable combinations" that would fall into the "desireable vintage" combinations.


One of the subjects was what effect on HP air flow had. Withing that discussion were discussions of parts that at the time only "select race teams" like Shelby had access to.

One of those were the iron "GT40 heads". Something I still haven't seen in person and at the time I did not know existed?

Well to cut to the chase, the discussion revolved around what stock 289hp heads flow. 190cfm. What they flow race pported and dangerously thin. 22cfm.

Then we had the iron GT40. Thought to be in the 240 vacinity.

We never got to Webers or what that manifold could flow so no need to go there but I asked if he had an idea of the number a stock C60A would show now and he theough 240. So complimentary to a GT40 head.


So we can get into what are good flow numbers are, etc., but with Curts comments about extrude honing his "repro" Blue Thunders and considering how even "Vintage racers" attempt to "extend their advantages" and keep those largely unseen and the fact that Cobra Automotive dynos those engines at 620hp, the combination of all of this stirred my interest even more.

So knowingly that there are some reasonably accurate tested flow numbers available for heads, I was just looking for those done on intakes.

Flow numbers are key indicators of the likely horespower potential available. They are not ultimates. There is enough "feeling in the field" for the adage that potential horsepower is often directly proportional to two times the cylinder head flow of one intake.

That much like the NHRA horsepower factors based upon vehicle weight, ET and trap speeds often seems more accurate then any advertised numbers.

I have only a limited experience with those factors but two comparisons that I remember were stock Boss429's being factored at 275hp and 428cj's at 400.


I would say that my observation now is suspiciously indicative that the intake numbers even at this point are proprietary. Simply put, no one wants to talk about it even now. Very curious indeed.  :)

I used to have a Superflow 600 bench. I can use per the deal of when I let it go to the new owner anytime I want. However now it is a 1,000 mile trip to where it is. I'm currently working on port matching a C6OE-A intake to a set of AFR cylinder heads for a 352" build on a Dart block. So I was pleased to see there was enough material to make the intake ports roughly a consistent 0.050" smaller all the way around.


We'll see how it goes.


John

I'm a C60A-A on a 347 with AFR heads. Somehow this monster likes BC-BD Holleys better then 2 1850's? I suspect there is quite a better flow then Mr.Gillis suggested?

Kind of difficult to take a virtually new intake and risk an Extrude Hone, especially if there is no reason to do it.

a C60A-A on a 347 with AFR heads. Somehow this monster likes BC-BD Holleys better then 2 1850's? I suspect there is quite a better flow then Mr.Gillis suggested?

Kind of difficult to take a virtually new intake and risk an Extrude Hone, especially if there is no reason to do it.

Agreed on the extrude hone, especially if you look inside and study what is there.


John

Yes. What I am seeing is a very close to equal length manifold at wide open throttle The length from throttle plate to intake valve at what is now derived at as optimal and a very high quality casting (almost pressure cast) with close to perfect shape internal ports their entire lengths, port exit shapes with a near perfect gasket match as cast and last but not least, internal port passages that match the OD of the BC-BD Holleys/

The accuracy of the casting is amazing and it was not cast up in someones back yard sand box. The pattern probably belongs in a modern industrial art museum. This manifold is serious stuff.

I doubt that it could be improved upon. Only ruined.

Without having my own flow bench, it just raises my level of curiosity at exactly what I am dealing with? Maybe an Area 51, reverse engineered Alien design? I've never seen anything from that era that even approaches this kind of accuracy in a casting and anything coming close to optimization like this?

It is almost a shame to get it dirty but almost impossible to resist running this mutha'?


The issue of #5 running lean on the "turd" eliminated. The only possible area to mess with is the plenum balance tube which is reduced in size from the WOT runners. I wouldn't even mess with that since it probably is already a balance of compromises to make the thing acceptable for idle and part throttle. There I wouldn't be shocked if the other variants were experimented with and vary?

This was not arrived at by guessing. Someone had a flow bench and wasn't using just a slide rule to analyze the results.

But as suggested, it was analyzed as a system with the heads but there is a suggestion to me that it may be partially a variable flow design because of the balance tube? Aliens can be strange.

I'm guessing it is closer to 280 cfm (perhaps  more) as a system which would make sense of why it runs so well at just off idle and part throttle on the BC-BD's and plays well with the AFR heads? Those were also Randy's suggestion.

The fact that all of the original design considerations were for maximizing 289's and this is one is on a 347 doesn't hurt the equation either, just makes everything more responsive to throttle input. The increase in engine cubic inches from 289 to 347 works in bring down rpm peaks to a more streetable number and out of the 8,000 rpm stratosphere.


Some ask why use a dual 4 when recent dynos show little benefit over a single 4? Something like 15hp more. It may be that 2-4's gives opportunity to better runner layout that a single 4 can't and that shows in much less cylinder to cylinder flow variation as cast? That is why I would be interesting to see what the single 4v Cobra, etc., does on a flow bench, stock and then modified.

Look at how the Torker and the Rousch attempt to equalize the runner lengths on a single 4.

Quote from: shelbydoug on December 31, 2024, 09:26:01 AMI searched everywhere with no results at all.

Have any of you found a source publishing tested results of '60s Ford performance intake manifolds CFM flow numbers? I can't find anything.

Head flow numbers are by comparison easy to find.

Have any of you done Extrude Hone on any of the intakes?


I seem to remember Cobra Automotive offering Extrude Hone on the Cobra high rise intakes but haven't talked to them recently about it.

I helped run dozens of FE intakes that Jay Brown used the results of to write his book "The Great FE Intake Comparo". If you use an FE in anything you need to read this book.

Quote from: shelbydoug on January 12, 2025, 07:21:28 AMThe only possible area to mess with is the plenum balance tube which is reduced in size from the WOT runners. I wouldn't even mess with that since it probably is already a balance of compromises to make the thing acceptable for idle and part throttle.

    Yes, the "balance tube" is a compromise development particularly attributed to the progressive carburetor linkage function, but to some degree is also utilized in aiding in balancing the flow sums more equally particularly between the two carburetors but also thought the intake manifold at W.O.T..  :)

    This probably indicating that if utilizing, say.............a pair of Holley List #4224, 660 C.F.M. "Center-Squirters", with 1 : 1 throttle linkage setup, and with testing, the balance or cross-over passage would probably be found to be excessively generous in size for "best performance".  :-\

QuoteSome ask why use a dual 4 when recent dynos show little benefit over a single 4? It may be that 2-4's gives opportunity to better runner layout that a single 4 can't and that shows in much less cylinder to cylinder flow variation..........

    One would need to quantify the first sentence to some degree in order to avoid an argument; but the next is absolutely a contributing factor!  :) 

QuoteThe fact that all of the original design considerations were for maximizing 289's and this is one is on a 347 doesn't hurt the equation either, just makes everything more responsive to throttle input.

    Well yes,............ but if the induction were truly "maximized" for an engine capacity of 289 cu.in.'s, then mounting such on an engine of 347 cu.in. 'is' going to change the experienced performance throughout the dynamic range of operation; probably simply put, one would expect greater throttle response and torque in the lower R.P.M. ranges, but with lesser peak R.P.M.'s for useful power production, and in the end 'perhaps', though at a lower R.P.M. for the latter, both engine examples may prove only equivalent in peak horsepower numbers.  ;)

    Scott.

Quote from: pbf777 on January 13, 2025, 11:51:58 AM

Quote from: shelbydoug on January 12, 2025, 07:21:28 AMThe only possible area to mess with is the plenum balance tube which is reduced in size from the WOT runners. I wouldn't even mess with that since it probably is already a balance of compromises to make the thing acceptable for idle and part throttle.

    Yes, the "balance tube" is a compromise development particularly attributed to the progressive carburetor linkage function, but to some degree is also utilized in aiding in balancing the flow sums more equally particularly between the two carburetors but also thought the intake manifold at W.O.T..  :)

    This probably indicating that if utilizing, say.............a pair of Holley List #4224, 660 C.F.M. "Center-Squirters", with 1 : 1 throttle linkage setup, and with testing, the balance or cross-over passage would probably be found to be excessively generous in size for "best performance".  :-\

QuoteSome ask why use a dual 4 when recent dynos show little benefit over a single 4? It may be that 2-4's gives opportunity to better runner layout that a single 4 can't and that shows in much less cylinder to cylinder flow variation..........

    One would need to quantify the first sentence to some degree in order to avoid an argument; but the next is absolutely a contributing factor!  :) 

QuoteThe fact that all of the original design considerations were for maximizing 289's and this is one is on a 347 doesn't hurt the equation either, just makes everything more responsive to throttle input.

    Well yes,............ but if the induction were truly "maximized" for an engine capacity of 289 cu.in.'s, then mounting such on an engine of 347 cu.in. 'is' going to change the experienced performance throughout the dynamic range of operation; probably simply put, one would expect greater throttle response and torque in the lower R.P.M. ranges, but with lesser peak R.P.M.'s for useful power production, and in the end 'perhaps', though at a lower R.P.M. for the latter, both engine examples may prove only equivalent in peak horsepower numbers.  ;)

    Scott.

Well I have no idea if the manifold actually maximized intake performance for a 289 but considering how experimentation is progressive and I see no "bigger attempt" I ASSUME that there was no "next step up" UNLESS there is and that is the dual Dominators on the Boss 302?-


In my case since this is a street car and I don't need to fight  (or pay for) minute increases in horsepower to fend off the competition, reaching maximum power and torque at a lower rpm then the seeming suicidal T/A racers of the day is a definite benefit to me. That is why I selected 347ci instead of 331 (or 289 or 302).
I don't need an 8,000 rpm limit and certainly the repair bills that will come with attempting to use that.

On that subject, however, it seems likely to me, that this setup liking the BC-BD, 715cfm carbs may be because of the larger displacement? The inside diameter of the intake runners suggests at least to me that there was design consideration for something more then 1850's. These runners match the throttle bores of the 3300/3301's.


It may have wound up with a pair of 1:1 660 center squirters but that was a later development. Not the initial application. It wasn't designed for those carbs because they didn't exist when it was. It had a pair of vacuum secondaries. Drivers complained that the vacuum secondaries didn't respond fast enough to closing the throttle. So Ford brought in Holley to fix the issue and inventing the 660's was that solution.


I suspect that there can be a "sweet spot" where the larger runners will work for both the 289 displacement and something larger. Velocity and volume are both maintained. That could be accidental but this thing is no less then an Alien Device with properties where the sum of the parts is greater then the whole?

This manifold was inarguably created with data beyond the realm of even super human abilities. Possibly the formula was accidentally found in the Akoshic Records that the Hindus speak of?


If I had infinite time and financing to experiment endlessly, it certainly would result in more data available to suggest if not prove exactly what is going on and why, but needless to say, I don't.

So I'm happy with the positive results considering that it could have been a terrible mismatch.

Again, it would be enlightening to see flow bench results on this setup? Something good is going on here.



I suppose I am like the Wizard of Oz in that I just came here in a hot air balloon that someone else built, but I don't know how the thing works and can't fix it?

Life is strange. Me too. :)

I agree that with a lower RPM limit theoretically on a larger engine you are playing in the same ballpark. As an example a 289 CID engine @ 8,000 RPM in theory flows as much at WOT as a 347 CID engine @ roughly 6,600 RPM. A much more reasonable number for a street car. However knowing you, you probably push another 400 RPM for a still reasonable 7,000 RPM redline.

The Harold Drost Holley carburetors (Sorry Randy, we must share the conversation with a larger audience now that you have passed. I kept my end of the bargain.) prior to the double pumper were a progressive linkage center squirter carburetor. These as you alluded to, work better than the vacuum secondary carburetors on deceleration and that is an important aspect of the functioning of the engine. In addition the Drost/Holley carburetors were smaller in CFM than the 660 carburetors, at around 590 CFM with bushed shafts and a special groove cut into the throttle actuating cam to provide a progressive linkage for increased on track drivability.  With a 20% larger engine and a 6,500 to 7,000 RPM redline my guess is that you are going in a great direction with the BC/BD carburetors.

As to "I ASSUME that there was no "next step up" UNLESS there is and that is the dual Dominators on the Boss 302?" That was really FoMoCo trying a work around on the "no Weber policy" the SCCA had with Trans Am. If you use the Weber formula with the 305 cubic inch 8,000 RPM input of the T/A BOSS 302 engine you will see that the big 1150 CFM carburetors fit the bill. Next step is to realize that in an IR application the depression on the venturing booster is roughly half of what it is in a plenum style intake system. Therefore those big old bad dominators are only flowing 575 CFM on the dual dominator intake manifold.... 🤔 Hmmm, pretty darn close to the 590 CFM carburetors I mentioned previously that were developed for the 302 Tunnelport and GT40 programs. So not actually as big a "Step Up" as it was a "how does this work" trial for the Trans Am series. As a side note Randy shared with me that in tests with multiple engines and intake manifold combinations in the same chassis after the 1968 season the drivers actually preferred the standard flange Holley dual plane/dual quad intake manifold with the 590 CFM carburetors on the BOSS 302 engine to the Dual Dominator equipped BOSS 302 engines. The theory is that the bean counters in Dearborn said that with all the funds invested in the Dominator system and since the max horsepower numbers were comparable the standard flange Holley dual plane/dual quad intake was not made a production part. Neither Randy or myself ever saw or knew of anyone who saw one of those intake manifolds with even an SK number cast into it. Only 10 were known to exist as of Randy's and my last big search. Yes it works far superior to the Shelby dual plane/dual quad BOSS 302 intake that more closely resembles the C6OE-A intake manifold that it was most likely developed from and requires an offset distributor as well.

In an unlimited time and money budget world I as well would be chasing more answers. For now I'm working on a 352 inch motor with the C6OE-A, an undetermined CID BOSS motor with the 1969 T/A intakes, and a 302 CID motor with Kelly Coffield's long runner IR Dual "B" Inline carburetor intake manifold. I'm sure I will still be looking for answers for a long long time. FoMoCo had more smarter folks than me, a bunch more of them than I do.


John

Quote from: JohnSlack on January 13, 2025, 07:32:24 PMI agree that with a lower RPM limit theoretically on a larger engine you are playing in the same ballpark. As an example a 289 CID engine @ 8,000 RPM in theory flows as much at WOT as a 347 CID engine @ roughly 6,600 RPM. A much more reasonable number for a street car. However knowing you, you probably push another 400 RPM for a still reasonable 7,000 RPM redline.

The Harold Drost Holley carburetors (Sorry Randy, we must share the conversation with a larger audience now that you have passed. I kept my end of the bargain.) prior to the double pumper were a progressive linkage center squirter carburetor. These as you alluded to, work better than the vacuum secondary carburetors on deceleration and that is an important aspect of the functioning of the engine. In addition the Drost/Holley carburetors were smaller in CFM than the 660 carburetors, at around 590 CFM with bushed shafts and a special groove cut into the throttle actuating cam to provide a progressive linkage for increased on track drivability.  With a 20% larger engine and a 6,500 to 7,000 RPM redline my guess is that you are going in a great direction with the BC/BD carburetors.

As to "I ASSUME that there was no "next step up" UNLESS there is and that is the dual Dominators on the Boss 302?" That was really FoMoCo trying a work around on the "no Weber policy" the SCCA had with Trans Am. If you use the Weber formula with the 305 cubic inch 8,000 RPM input of the T/A BOSS 302 engine you will see that the big 1150 CFM carburetors fit the bill. Next step is to realize that in an IR application the depression on the venturing booster is roughly half of what it is in a plenum style intake system. Therefore those big old bad dominators are only flowing 575 CFM on the dual dominator intake manifold.... 🤔 Hmmm, pretty darn close to the 590 CFM carburetors I mentioned previously that were developed for the 302 Tunnelport and GT40 programs. So not actually as big a "Step Up" as it was a "how does this work" trial for the Trans Am series. As a side note Randy shared with me that in tests with multiple engines and intake manifold combinations in the same chassis after the 1968 season the drivers actually preferred the standard flange Holley dual plane/dual quad intake manifold with the 590 CFM carburetors on the BOSS 302 engine to the Dual Dominator equipped BOSS 302 engines. The theory is that the bean counters in Dearborn said that with all the funds invested in the Dominator system and since the max horsepower numbers were comparable the standard flange Holley dual plane/dual quad intake was not made a production part. Neither Randy or myself ever saw or knew of anyone who saw one of those intake manifolds with even an SK number cast into it. Only 10 were known to exist as of Randy's and my last big search. Yes it works far superior to the Shelby dual plane/dual quad BOSS 302 intake that more closely resembles the C6OE-A intake manifold that it was most likely developed from and requires an offset distributor as well.

In an unlimited time and money budget world I as well would be chasing more answers. For now I'm working on a 352 inch motor with the C6OE-A, an undetermined CID BOSS motor with the 1969 T/A intakes, and a 302 CID motor with Kelly Coffield's long runner IR Dual "B" Inline carburetor intake manifold. I'm sure I will still be looking for answers for a long long time. FoMoCo had more smarter folks than me, a bunch more of them than I do.


John

If the 3300/3301 turn out to be unrealistic somehow, the 1850's are fine. It seems ironic that they actually idle much better and are smoother? Go figure?
I have them off right now and the 1850's on just because I can't believe that they can possibly be right? Even after driving the car, but the 1850' just don't pull as hard.


Randy did warn me about the Shelby dual 4 B2 intake. He said "it didn't work. Don't bother to go that way".


I'm not sure that anyone can prove why any of these work, just theorize why they do. I'm thinking that there was more development work needed to do to make the B2 version work with the balance tube. I think that is the tuneable part?


I'm sure that all of us are influenced by some of the  "racer's adages" simply because there is a lot of mileage and experience that went into those conclusions even though they couldn't work a slide rule.

Two that I can think of is that "air flow x2 = horsepower" and "carb cfm = 2x cid". Those numbers seem to agree more times then not?


Although I admit that you have correctly surmised my rpm thinking I am like the comedian Robert Klein in that "I can't stop my foot". It simply has a mind of its own so the only safe thing to do is an rpm limiter and "safe valve springs".

I miss Randy too. He was on my case to bring my car to the west coast. He wanted to see it run but I think he just wanted to race me. He kept threatening me with unrealistic classifications where essentially I'd be running against Pro-stock like modified cars. He said mine was just to modified to let run against stockish GT350's, the SOB!  :)


After "playing" with these cars for over 50 years, I've constantly had to reinvent myself to keep interested. At this point the C60A has just run fresh blood into the old veins. To think that the tech crews that designed, built, developed and immortalized things like this were living back then on probably a $150 a week pay day is just incredible.


Even Elton John dreamed about those days when he sang to Marilyn Monroe. "I would have loved to love you but I was just a kid". And he is gay. So those days fascinate many of us even in unrealistic ways?

It was just a fascinating time. It encourages me to realize that we are still living in a golden age and for me pulling something of this level out of a time machine gave me a new burst of energy?


I went with Webers on my Pantera. I had a B2 Doug Nash magnesium split intake but I couldn't nail down a pair of inlines. Kelly would buy them out from under me. Ancient history and sent me to the Weber route. That was 1978ish. No regrets.


I can say that what I found with the 351c, that a 4779 750dp was just a bit large for it. A 700dp was about right but the Boss 302 735cfm Holley with the vacuum secondary wasn't right either. It wasn't as responsive as the DP was.

Presuming that a 350ci engine is about right with a 700ish carb. Running with the BC/BD's I can see where they are working as a "700 something dp" with afterburners? I can hear the secondaries open and they make a heck of a racket when they do. You can see the nose of the car coming up. It's just a little bit violent, shudders the car and it kind of reminds me of how "slick shake", shakes the car? So I do not think it is over carbed at all.

IF we are speculating on why the big carbs work on the 347, 1.2 x 590 = 708. That is suggestive of what is going on and why the big carbs are working.
I can't think of an equation that predicts the level of my irrationality at this moment? Maybe someone else can?

Why the BC/BD idle better and have better part throttle manors was suggested by Drew in that they have the ideal ratio of venturi size to throttle bore.


Is there a difference between the C60A and the C60E besides the casting numbers and for that matter the SHELBY tagged no numbers version? Besides the casting ID's, the outside looks the same? Does the internal size of the balance tube vary?


I feel like Indiana Jones discovering a long abandoned "City of Gold" built by a higher level of technology that somehow has been lost over the decades?


All very interesting and definitely going to keep me busy for quite a while. Now it has me thinking if the camshaft is optimized and I think I am one level small on that? It never stops I suppose until you are dead?
Oh, this is an A/C car too. It's no wonder the neighbors are all terrorized by the old guy with the long grey hair. "Better be nice to him. Might be one of those radical '60s 'Hippies'?"

Quote from: JohnSlack on January 13, 2025, 07:32:24 PMNext step is to realize that in an IR application the depression on the venturing booster is roughly half of what it is in a plenum style intake system. Therefore those big old bad dominators are only flowing 575 CFM on the dual dominator intake manifold.... 🤔 Hmmm, pretty darn close to the 590 CFM carburetors I mentioned previously that were developed for the 302 Tunnelport and GT40 programs. So not actually as big a "Step Up" as it was a "how does this work" trial for the Trans Am series.

    John,

    I'm not sure that I'm reading this statement as you might have meant it to be understood (and of course, this may solely be me :-[ ); this as in the the "peak" depression value as experienced through the carburetor venturi, and hence acting upon the booster venturi, of the I.R. manifolding is generally significantly greater than that of the plenum style induction manifolds; but obviously isn't as constant, with reversals that often spike the pressure through the venturi's above atmospheric, again to sums far greater than that of the latter.

    But I suppose, if one were to average these values over a duration of time, then perhaps the meaning in your statement might prove more relevant.  As if the same engine produces approximately the same H.P., even with two different induction systems, then the total air flow sums here, in general, are considered pretty much a constant. But in the instance of the I.R. induction system, with the lack of a plenum effect and volume, this sum of atmosphere volume must pass through the venturi in less time.   :)

    Scott.

This video about flow testing a Shelby COBRA intake manifold although modified with porting may be of interest to some.

https://youtu.be/wZ-ZW2J3Occ?si=9A5TqrRl_Mb-qUj9

Quote from: pbf777 on January 14, 2025, 11:08:33 AM

Quote from: JohnSlack on January 13, 2025, 07:32:24 PMNext step is to realize that in an IR application the depression on the venturing booster is roughly half of what it is in a plenum style intake system. Therefore those big old bad dominators are only flowing 575 CFM on the dual dominator intake manifold.... 🤔 Hmmm, pretty darn close to the 590 CFM carburetors I mentioned previously that were developed for the 302 Tunnelport and GT40 programs. So not actually as big a "Step Up" as it was a "how does this work" trial for the Trans Am series.

    John,

    I'm not sure that I'm reading this statement as you might have meant it to be understood (and of course, this may solely be me :-[ ); this as in the the "peak" depression value as experienced through the carburetor venturi, and hence acting upon the booster venturi, of the I.R. manifolding is generally significantly greater than that of the plenum style induction manifolds; but obviously isn't as constant, with reversals that often spike the pressure through the venturi's above atmospheric, again to sums far greater than that of the latter.

    But I suppose, if one were to average these values over a duration of time, then perhaps the meaning in your statement might prove more relevant.  As if the same engine produces approximately the same H.P., even with two different induction systems, then the total air flow sums here, in general, are considered pretty much a constant. But in the instance of the I.R. induction system, with the lack of a plenum effect and volume, this sum of atmosphere volume must pass through the venturi in less time.   :)

    Scott.

Scott,
My information as to depression differences based on a plenum intake manifold vs. an IR intake came from Dick Carr as a rule of thumb. Dick was a representative of Holley carburetors and one of the Unlimited Class Air Racing Tech inspectors when we were racing the Bearcat for a while. Dick was with Holley when the 4600 series of the really big Dominator was being developed. He offered me a pair of them when Holley gave up on them, but like Holley I couldn't imagine what to do with them either.....



John

Quote from: NukeGT on January 14, 2025, 10:25:31 PMThis video about flow testing a Shelby COBRA intake manifold although modified with porting may be of interest to some.

https://youtu.be/wZ-ZW2J3Occ?si=9A5TqrRl_Mb-qUj9

Nice. Thank you. I want to see the heads though? GT40's? I can't believe those could be stock iron 289 heads, even ported ones? Not with those numbers?

I'm a bit surprised at the stock out of the box COBRA single four with 240 runners, being that good but HP results of 425-475 ish is what I've seen in actuality with a single 4 no matter what carb was picked. Kiwi's dynoed at 425hp with 331 cubes. I don't recall at what rpm but maybe around 6,600 rpm?


At some point someone will discover the C60A numbers but I'd predict a 500+ hp with it. Maybe even 550? It seems kind of obvious that it has better runner layout for more equal flow balance?

There is a LITTLE bit of the high low runner issue in the plenums with it also like the single 4 COBRA intakes so that can't be eliminated unless you go to a straight tunnel ram or someone from the science fiction group can create a zenomorph intake that varies itself in form and shape as the situation demands. After all, the C60A is a hybrid. A bit of a platypus with characteristics of more then one species.
And how the "balance tube" varies from engine application to application has not been touched upon except to say that the "Windsor" configuration does not work on the "Boss heads" as a direct transplant. That is why I asked in a previous post about that.

Thin castings is something touched upon in the video and something that I am aware of in both the intakes and the heads themselves. The C60A looks even thinner then the COBRA and the only thing that might be possible on it would be an extrude hone but who would want to risk that?


Where Cobra Automotive is getting 620hp is a bit of a mystery to me but a nice number to dream about? With 292ci you probably have to turn it 8,000? 500hp would be a very nice but huge number in the day especially considering that published numbers from the Shelby engine shop claimed 366hp. Now 500 to 620 is quite a discrepancy.  Have alchemists switched from turning lead into gold to engine building?


It's amazing what you (me) can learn if asking the right questions and a key indicator is that I am irritating those in the know enough to the point that they can only hold their tongue for so long without bursting and posting a reply of corrections with what they know? Realize that these are leading questions by me and with statements to encourage that.

All very interesting gentlemen. Carry on please.

Hi! Finding CFM flow data for '60s intakes is tough. Cobra Automotive did offer Extrude Hone on high-rise intakes, so reaching out to them might help. As for published results, most seem to come from individual testing, like dyno runs—specific publications are rare.

Adding: Try checking Mustang or Shelby forums—folks there sometimes share custom test results. Extrude Hone really improves flow consistency, so it's worth exploring. Let us know if you find anything! 😊 (https://przestronnie.pl/)

Quote from: Zelda on January 17, 2025, 03:47:37 AMHi! Finding CFM flow data for '60s intakes is tough. Cobra Automotive did offer Extrude Hone on high-rise intakes, so reaching out to them might help. As for published results, most seem to come from individual testing, like dyno runs—specific publications are rare.

Adding: Try checking Mustang or Shelby forums—folks there sometimes share custom test results. Extrude Hone really improves flow consistency, so it's worth exploring. Let us know if you find anything!  :)

Zelda
Big plus one

The lac

Quote from: Zelda on January 17, 2025, 03:47:37 AMHi! Finding CFM flow data for '60s intakes is tough. Cobra Automotive did offer Extrude Hone on high-rise intakes, so reaching out to them might help. As for published results, most seem to come from individual testing, like dyno runs—specific publications are rare.

Adding: Try checking Mustang or Shelby forums—folks there sometimes share custom test results. Extrude Hone really improves flow consistency, so it's worth exploring. Let us know if you find anything!  :)

The lack of any response from them was a key motivator to initiating this post to begin with.

If and when I get any response I intend to share but don't feel encouraged so far.

     In my observations, the "Extrude-Hone" process and resultant effect, as generally practiced, presents little more than a surface smoothing result; handy for manifolding that is of greater lengths and complexity than true hand or CNC porting would permit for, but not effectively capable of all of that which one generally expects from a properly ported for best performance manifold example.  ;)

     In my opinion, the best application of the extrude-hone process would be as a final treatment, this 'after' conventional porting work had been done where selective material arrangements are made and afterward all is then "polished-up".  :)

     Scott.

     

Quote from: shelbydoug on January 15, 2025, 08:17:17 AMWhere Cobra Automotive is getting 620hp is a bit of a mystery to me but a nice number to dream about? With 292ci you probably have to turn it 8,000? 500hp would be a very nice but huge number in the day especially considering that published numbers from the Shelby engine shop claimed 366hp. Now 500 to 620 is quite a discrepancy.

      A couple of dozen and more years ago we were building "truly legal" F.I.A. 289's that 'were' durable and clearing 450+ H.P..  But today there has been a significant increase in the availability of specialty "replacement" parts and rule adjustments that are permitting greater sums of power; not to mention, it seems no one is actually building "truly" legal examples, or at least not anything that would represent a "truly vintage" example these days! 

      This is not to say that all of the numbers being toss around are accurate; but then, when in history did anyone actually believe any of the horsepower numbers ever having been bantered around as being accurate and not having been "adjusted" for one reason or another?   ::)

      Scott.

Your point is well taken by me.

The only reason I even brought up the subject was the mentioning of it in a discussion with Cobra Automotive.
In it, it was mentioned that with the Blue Thunder version, on their flow bench, the before and after was a plus 10%.

So if that is in fact accurate and not just bluster, the suggestion is that the Blue Thunder went from an average runner flow of 240cfh to 264cfm. That is a nice increase but I'm not sure if I would consider it economical at $750 for the process? Now that wasn't part of my initial question and rather then the COBRA single 4v, I was more interested in the various flow numbers on the T/A versions.

Those runners volumes are more generous in cross sectional area already, shorter and more direct in WOT mode. So first of all, the only base number that I have is what Randy thought they would be as cast at right around 240cfm, which is what he had documentation on for the iron GT40 heads.

Extrude hone on a C60A may just be more effective on the T/A's simply because of the differences in the runner designs? All speculation on my part but it is pretty cold and snowy here now so what better things do I need to do to keep busy?

Quote from: pbf777 on January 20, 2025, 12:11:47 PM

Quote from: shelbydoug on January 15, 2025, 08:17:17 AMWhere Cobra Automotive is getting 620hp is a bit of a mystery to me but a nice number to dream about? With 292ci you probably have to turn it 8,000? 500hp would be a very nice but huge number in the day especially considering that published numbers from the Shelby engine shop claimed 366hp. Now 500 to 620 is quite a discrepancy.

      A couple of dozen and more years ago we were building "truly legal" F.I.A. 289's that 'were' durable and clearing 450+ H.P..  But today there has been a significant increase in the availability of specialty "replacement" parts and rule adjustments that are permitting greater sums of power; not to mention, it seems no one is actually building "truly" legal examples, or at least not anything that would represent a "truly vintage" example these days! 

      This is not to say that all of the numbers being toss around are accurate; but then, when in history did anyone actually believe any of the horsepower numbers ever having been bantered around as being accurate and not having been "adjusted" for one reason or another?   ::)

      Scott.

620hp is a big claim. A "True Grit" one in fact. And just like in "True Grit", "it's mighty big talk for a one eyed fat man!"  ;D


So really if I consider the adage of hp = 2 x air flow, at 450 and 240 your resulting numbers tend to agree.

To get to 620 the air flow should be more like 300cfm? As I said, "mighty big talk".

I'm not blind and fat enough YET to make those kind of claims.


I did see the #1 C/A car run until it blew the engine in practice. Then saw the back up car and there was a big difference.
Whereas the #1 was leading the pack, the backup had difficulty keeping up. There was more then witchcraft involved in that. I don't get involved in that. I already have enough curses cast on me. I don't need more.

Quote from: shelbydoug on January 20, 2025, 12:20:40 PM............ it was mentioned................., on their flow bench, the before and after was a plus 10%.

So if that is in fact accurate and not just bluster,.............. That is a nice increase but I'm not sure if I would consider it economical at $750 for the process?

      Well, if one wants to be competitive, porting work is a requirement!  ;)

      And as one whom has been in the business of executing porting work in the past, a 10% port flow increase is an aggressive, but not necessarily unreasonable expectation (here); that with the proper effort put forth.  But stop, and think about the time element involved in accomplishing this?  And at $750., I can't pay a guy to sweep the floors for the resultant hourly rate that would be commensurate with the number of hours I'd have invested in accomplishing this task properly!   :o

      So, what are you actually getting, for what is actually a pittance of a charge, for the effort (supposedly) being put forth?   :-\

      Scott.

Quote from: pbf777 on January 20, 2025, 02:10:34 PM

Quote from: shelbydoug on January 20, 2025, 12:20:40 PM............ it was mentioned................., on their flow bench, the before and after was a plus 10%.

So if that is in fact accurate and not just bluster,.............. That is a nice increase but I'm not sure if I would consider it economical at $750 for the process?

      Well, if one wants to be competitive, porting work is a requirement!  ;)

      And as one whom has been in the business of executing porting work in the past, a 10% port flow increase is an aggressive, but not necessarily unreasonable expectation (here); that with the proper effort put forth.  But stop, and think about the time element involved in accomplishing this?  And at $750., I can't pay a guy to sweep the floors for the resultant hourly rate that would be commensurate with the number of hours I'd have invested in accomplishing this task properly!  :o

      So, what are you actually getting, for what is actually a pittance of a charge, for the effort (supposedly) being put forth?  :-\

      Scott.

That was the original selling point of the extrude hone. I have done a bit of porting myself.

The last set of heads that I did sold for $500 with new bigger valves, a couple of days or more worth of grinding plus the customary competition valve job.
Ultimately the selling price was just to move them out of the way since they were old news and I had moved on.

Thinking of people like Kaase, in order for him to be competitive in these engine building competitions, he can't even pay himself I'm very sure.

It is the nature of the beast even if you now have a CNC robot?


I've already acknowledged that much of this development work was done initially in the mid '60s and likely the payday back then per man was in the $150 a week area, even though being funded (in this case) by Ford. It kind of easily justifies buying aftermarket cnc'd heads even if the advertised flow numbers are over stated some. They are done as they come in the door and you can just bolt them on.



I am largely agreeing with you on all written but this really is all academic at the moment? Since I am hearing crickets on my intake inquiries, not numbers so far? But just base numbers, tested as cast, even old ones would help in explaining even old approaches and maybe emphasize how lucky we are now to get even old tech, high performance items for less then what dirt costs now? But I already have realize how fortunate I have been in even having owned some of this "King of the Hill" stuff even momentarily.

Even carburetors are to the point of being museum pieces.


Here's an artists drawing of me as a boy walking my dinosaur. It was a Tyrannosaurus Rex. Even then I had the biggest and meanest. It is actually a photo of the art which was done on the wall of the cave where I was brought up in. It isn't black chalk. It is a cooled burnt piece of charcoal wood from the fire place. Cameras and art supplies didn't exist then yet.

Doug,
Ford learned a whole bunch between the C6OA-A intake and the stillborn no part number BOSS 302 intake manifolds, I put them on the bench together for the first time. As I'm doing work on the C6OA-A intake manifold I took my Depstech camera and wandered through the ports, including the balance tubes. The balance tubes are well finished in typical casting finish. I would describe them as generous in proportion. I think I have to disagree with you on the "equal length" I can see similar length for #s 1,5,7 & 3, with much short and more direct lengths on #s 2,4,6,& 8. However I can agree with you on that Randy Gillis put me on to both of these intake manifolds (The C6OA-A and BOSS 302 T/A Std. Flange dual plane 2x4 intake) as the best in class by far for each head configuration. The Ports in the BOSS 302 intake manifold and the balance tube area are of course "cavernous" in proportion to the C6OA-A intake. And the BOSS 302 intake is actually pretty darn close to equal lengths in the runners. The down side of that is the need for additional rare hardware in the offset distributor.


I'd also love to get flow numbers on the intake manifolds, but I'm guessing that with all of the balance passages the only real answer is to meter the air going through the engine actually on a dynamometer. Which adds more questions than answers... correct?

Glad to see you had a T-Rex as a child, however all of our FE friends laugh at us when we consider any small block a beast... probably for good measure, eh.


John

Filed under if anyone knows:

Did NASCAR teams (then or now) do manifold flow testing, not that they would reveal what they found, but details might have eventually leaked.

In discussing manifold flow, does reverison into the runner when the intake opens have any flow impact or is it too small to notice.

per Zora Arkus-Duntov: ". . .one man's thinking aloud on the subject."

Quote from: JohnSlack on January 20, 2025, 11:38:21 PMDoug,
Ford learned a whole bunch between the C6OA-A intake and the stillborn no part number BOSS 302 intake manifolds, I put them on the bench together for the first time. As I'm doing work on the C6OA-A intake manifold I took my Depstech camera and wandered through the ports, including the balance tubes. The balance tubes are well finished in typical casting finish. I would describe them as generous in proportion. I think I have to disagree with you on the "equal length" I can see similar length for #s 1,5,7 & 3, with much short and more direct lengths on #s 2,4,6,& 8. However I can agree with you on that Randy Gillis put me on to both of these intake manifolds (The C6OA-A and BOSS 302 T/A Std. Flange dual plane 2x4 intake) as the best in class by far for each head configuration. The Ports in the BOSS 302 intake manifold and the balance tube area are of course "cavernous" in proportion to the C6OA-A intake. And the BOSS 302 intake is actually pretty darn close to equal lengths in the runners. The down side of that is the need for additional rare hardware in the offset distributor.


I'd also love to get flow numbers on the intake manifolds, but I'm guessing that with all of the balance passages the only real answer is to meter the air going through the engine actually on a dynamometer. Which adds more questions than answers... correct?

Glad to see you had a T-Rex as a child, however all of our FE friends laugh at us when we consider any small block a beast... probably for good measure, eh.


John

Actually it was a "family T-rex". My Father would tell me to take him for a walk after my Mother would yell," I'm not cleaning that up!".
It was actually the saber tooth tiger that was the problem. He would spray everything to mark his territory which included my personal possessions as well! Yuck. It stunk!

I'm not immune to big blocks. There doesn't seem to be much science involved in them though? My 67 GT500, you just kind of point and hang on and it just goes where it wants to.

It is kind of like Hulk Hogan, both in appearance and performance. Not much intelligence going on there at all? Like a Defensive nose tackle. I'm more of the "fake you out quarterback type". Often causing problems because I thought I was smarter then the defense? It is humbling to be out thought by a bunch of Neanderthals.


I actually took a cloth tape measure that I borrowed from my wife's sewing box and measured the length of the runners
internally on the C60A. That was enough evidence for me to call them equal length. That tape measure does not stretch at all. They are within an inch of each other along the top of the ports where the snug tape would sit.

Remember, you will never know with me if I made a misstatement about something intentionally or just unknowingly. I find I get more response from those because others need to correct me with the actual data. :)
Kind of like how Scarecrow gets the apple trees to throw apples at him.


The B2 version is really very curious. It would be very interesting to combine them with the "recent" C302 heads to see if they like each other?

Interesting that it would seem that the significant difference between that one and the Shelby script B2 version is the carb positioning. I do remember Randy saying that but I thought he was talking about the rear carb, not the front? He was talking about the rear carb secondaries hanging out the back too far to be useful, on the Shelby script intake. He never mentioned the front carb positioning as I recall?


On my C60A, I thought that I had noticed a closing down of the balance tube into the front plenum by around 50%,  which is why I am curious about variations like if the C60E is different? Maybe mine needs an angioplasty on the balance tube?


Do you have any of those Ford "Cleveland" aluminum heads out of the "Indy Program"? The ones with the cast in radical high port exhausts like Nicholson wound up with on the iron Pro-Stock heads?

Randy said he bought out Nicholson's stuff at some point. Mentioned the aluminum blocks but don't remember him mentioning the heads?


On the extrude hone, my thought initially was that was essentially just an internal polishing of the runners but in thinking about head porting, mostly, that is also. As Scott pointed out, a 10% increase is a nice number considering the alternative procedures available at a much greater expense?

Quote from: 68countrysedan on January 21, 2025, 02:07:08 AMDid NASCAR teams [THEN] do manifold flow testing, not that they would reveal what they found, but details might have eventually leaked.

    I'd have to say that beyond the manufactures initial design stage of development where establishment of manifold function was being considered, the rest probably fell under the statement of:

Quoteauthor=JohnSlack link=msg=209911 date=1737434301]
I'd also love to get flow numbers on the intake manifolds, but I'm guessing ............. the only real answer is to meter the air going through the engine actually on a dynamometer.

     Or, just the resultant performance on the track! 

     Next:

QuoteIn discussing manifold flow, does reversion into the runner when the intake opens have any flow impact or is it too small to notice.

    This issue does not appear in the typical flow-bench testing process, but has come to light to those whom start to consider the fact that:

Quote from: JohnSlack on January 20, 2025, 11:38:21 PMthe only real answer is ................................... actually on a dynamometer. Which [often] adds more questions than answers... correct?

    Correct!    ;D 

    Scott.

When I went in this direction of the C60A the "feasibility study" that I did was that for a 8.2" Ford small block engine of the era, that I wanted to look at least period correct, that intake was pretty much the best that I was going find.

Everything else it provided, if anything, was just a bonus.

    Also, I think here we're getting to enthralled with the existence and possible effects of the "balance-tube", as we're not truly designing or redesigning an intake manifold from scratch; simply consider it as the established necessary concession for better carburetor function and fuel distribution not really having any great effect on flow-bench testing.   :-\

    And considering the dynamics, this probably is one of those things that are better "tested" in actual function, rather than on a bench or on paper.  ;) 

    Scott.   

Quote from: pbf777 on January 21, 2025, 12:08:50 PMAlso, I think here we're getting to enthralled with the existence and possible effects of the "balance-tube", as we're not truly designing or redesigning an intake manifold from scratch; simply consider it as the established necessary concession for better carburetor function and fuel distribution not really having any great effect on flow-bench testing.   :-\

    And considering the dynamics, this probably is one of those things that are better "tested" in actual function, rather than on a bench or on paper.  ;) 

    Scott.   

I look at the balance tube as the device added to make the engine able to idle on just the primary carb. Nothing more really.

Considering it was initially conceived of as possibly being a street production item, the initial carbs were vacuum secondaries with progressive linkage between the two carbs so the thinking on the balance tube had to have included a part throttle equalization as well. It truely is a hybrid and all considered, works pretty well and in addition has the flexibility to ditch the vacuum secondaries and go with mechanical 1:1 throttles.

That just may be an unintended benefit but who cares if it was an accident? Take credit for it since if it didn't work someone would for sure have been blamed for being an idiot?

I'm very happy to be a temporary caretaker. I hope the next owners will appreciate it as well?

I know someone who has his sitting on his dresser in the bed room. He looks at it everyday. He doesn't want to get it dirty? I suppose that's another way to go with it? It is pretty and after all, when installed is buried under all of those carbs.

Since Most folks don't know what we are talking about;

(https://i.imgur.com/7W86TMB.jpeg)
C6OA-A Shelby 2x4 Intake manifold with two 9776 450 CFM carburetors, This is a T/A Intake for the 289/302. Bud Moore could not get this intake for the Cougars, FoMoCo wanted Ford to win.

(https://i.imgur.com/zSZbBoa.jpeg)
The no part number 1969 BOSS 302 Std. Flange Holley Dual plane 2x4 intake manifold. They tested this intake and according to reports the driver's liked it better than the Dual Dominator intake the team cars got for 1969. Although this intake was rumored to be available to FoMoCo privateer teams it was not. The developement of this intake was stopped when the Dominator Intake got the nod. Notice that the carburetors were moved forward to center the carburetors over the engine equalizing the ports. This intake manifold is flat and the same height as the dominator intake so that if forced by the sanctioning body FoMoCo did have a realistic bullet in their pocket. Also notice the 465 CFM Center Squirter SK carburetors that have their own progressive linkage, Drivabilty was enhanced for the track (Much better than 1:1 for that application). Those carburetors were built by Harold Droste at Holley for either the small block GT40 program or the Tunnelport 302 program. Randy looked them up in his carburetor log book, however he could not identify which they were made for.

(https://i.imgur.com/fbGA0lX.jpeg)
An overview of both intakes with the C6OA-A intake in front.

(https://i.imgur.com/ITexvbI.jpeg)
An overview of both intakes with the BOSS 302 intake in front.
When I leave this world I'm taking that intake with me. LOL


John


 

I've got the C60A. The B2 is even better.
 
Do you actually put those on the cars or just sleep with them?


I think that I understand why pictures were always being taken with hot sexy models. The girls were just trying to get someones attention away from things like this and notice them?  I wonder if that worked for any of them at all?


You and Randy thought that there were only 10 of them made?


Did you ever try different boosters on those carbs. The BC-BD's have down legs. I think that helps make them more responsive?

I just put annular's in the fronts of the 1850's and down legs in the back. I haven't tried them yet because the ice and snow are here and today it's a brisk 18° but at least we aren't on fire. Not yet anyway.

Quote from: JohnSlack on January 21, 2025, 03:07:57 PMAlso notice the 465 CFM Center Squirter SK carburetors that have their own progressive linkage, Drivabilty was enhanced for the track (Much better than 1:1 for that application). 

    Just to clarify:  Whereas other 8V installations common to F.M.C. production were of an intention of the carburetors being "progressive" or of "staged" throttle linkage motion relationship to one another, here I believe the two carburetors 'were' throttle linked as 1:1, meaning the primary throttle butterflies in both carburetors presented equivalent manipulation, just that the mechanical (vs. vacuum) secondary opening in each was of a progressive nature.    :)

    And, this is as was intended and typical of the "Center-Squirters" linkage set-ups; though in some instances one will find that the linkage plate's profile slot that regulates against the roller for the secondary opening effect gets "profiled" some which can create other unique instances. But also, as was offered through the aftermarket, there were "kits" available to convert the as delivered from Holley progressive secondary opening to a 1:1 process; this being most popular with the 8V tunnel-ram equipped "Drag-Guys".  8)

    Scott.

   

     

Quote from: pbf777 on January 21, 2025, 04:30:49 PM

Quote from: JohnSlack on January 21, 2025, 03:07:57 PMAlso notice the 465 CFM Center Squirter SK carburetors that have their own progressive linkage, Drivabilty was enhanced for the track (Much better than 1:1 for that application). 

    Just to clarify:  Whereas other 8V installations common to F.M.C. production were of an intention of the carburetors being "progressive" or of "staged" throttle linkage manipulation in relation to one another, here I believe the two carburetors 'were' throttle linked as 1:1, just that the secondary opening in each was of a progressive nature.  :)

    And, this is as was intended and typical of the "Center-Squirters" linkage set-ups; but, as was offered through the aftermarket, there were "kits" available to convert the as delivered from Holley progressive secondary opening to also a 1:1 process.  8)

    Scott.

   

     

Scott,
You are correct these two carburetors were connected so as movement on the front throttle shaft was mirrored 1:1 on the rear throttle shaft, the progressive behavior of the carburetor was through the shape of the slot in the linkage. The secondary shaft has a roller that rides in the slot and provides a very positive action both in opening and closing. During Randy's lifetime he amassed quite a collection of the Harold Droste SK carburetors. When these became available to me I inquired with my friend Bob Harris about them. Bob told me that I should take possession of the carburetors before asking Randy about them.

Randy was very happy for me to have acquired them and was very supportive to me. He provided a lot of details, while asking me to keep low key about them. There are certain details that most don't know about. Believe it or not Randy found most of his Droste carburetors at the Pomona or Long Beach swap meets. Some were just housings that most people didn't know what they were. So I have not shared anything while he was alive.


John

Quote from: shelbydoug on January 21, 2025, 03:29:51 PMI've got the C60A. The B2 is even better.
 
Do you actually put those on the cars or just sleep with them?


I think that I understand why pictures were always being taken with hot sexy models. The girls were just trying to get someones attention away from things like this and notice them?  I wonder if that worked for any of them at all?


You and Randy thought that there were only 10 of them made?


Did you ever try different boosters on those carbs. The BC-BD's have down legs. I think that helps make them more responsive?

I just put annular's in the fronts of the 1850's and down legs in the back. I haven't tried them yet because the ice and snow are here and today it's a brisk 18° but at least we aren't on fire. Not yet anyway.

Doug,
The C6OA-A intake is not mine, I'm setting it up for a friend for his '66 GT350. Believe me it will be driven and it will be run at full song. Yes using all of the tricks at my fingertips I have port matched that intake to a set of the AFR 205 CC heads, blasphemy? Not really I modified a perfect untouched intake in an area where Dan Case suggested that the Shelby intakes were worked on.

The BOSS 302 intake manifold is going on my 1969 1/2 BOSS 302. for years I kept a fairly complete collection of NOS intake manifolds and carburetors based on being flexible with a focus on the T/A intake manifold combinations. In this regard I recently let go of my Mini-Plenum (traded not sold) as I am settling into my final decision for both cars. They also will be driven.


John

What does the B2 look like without the carbs mounted?

Quote from: shelbydoug on January 21, 2025, 07:21:41 PMWhat does the B2 look like without the carbs mounted?

See if this link works;

https://www.boss302.com/smf/index.php?action=dlattach;attach=1208032;image

Follow this link you can see what Randy was discussing about the extreme rear overhang on the SHELBY lettered intake manifold.

https://www.boss302.com/smf/index.php?msg=605843

The UNICORN is aptly named.

I never looked for two balances tubes. It is more obvious on this one.

The pattern makers sure were kept busy. They are all different.

If the Dual Dominator flows 1/2 of the carbs rating, why does it make more power then the Unicorn?


One of the last conversations that I had with Randy was about the DD. He was asking me if I ever could do anything to fix the reversion on the Webers. He had just been working on the car, your car I presume, and talked about a plate installed over the carbs that was intended to accumulate the fuel reversion droplets and drain them to a "safe area".

He knew about the "Weber cam" that Compcams has but said that was not an option for the "race car".


I find it interesting that we all have similar experiences that we have dealt with individually at significant mileage differences. Compodres, brothers from different mothers?

Quote from: shelbydoug on January 21, 2025, 10:32:39 PMThe UNICORN is aptly named.

I never looked for two balances tubes. It is more obvious on this one.

The pattern makers sure were kept busy. They are all different.

If the Dual Dominator flows 1/2 of the carbs rating, why does it make more power then the Unicorn?

Not Sure it does, Randy said more maximum horsepower with the Dual Dominator IF you could keep it in tune.

Quote from: shelbydoug on January 21, 2025, 10:32:39 PMOne of the last conversations that I had with Randy was about the DD. He was asking me if I ever could do anything to fix the reversion on the Webers. He had just been working on the car, your car I presume, and talked about a plate installed over the carbs that was intended to accumulate the fuel reversion droplets and drain them to a "safe area".

Nope, Not my car, Randy knew i liked to be taught to fish, not to be fed already caught fish. So he would drop hints and monitor my frustration with the results. The car was the old Gurney Team Shelby Trans Am car, and the Warren Tope T/A car.

Quote from: shelbydoug on January 21, 2025, 10:32:39 PMHe knew about the "Weber cam" that Compcams has but said that was not an option for the "race car".


I find it interesting that we all have similar experiences that we have dealt with individually at significant mileage differences. Compodres, brothers from different mothers?

Price Motorsport has a dual four intake manifold for a 351W.
I never had this one in hand and the pictures posted are limited.
When I spoke to them, they claimed a port flow of 285cfm per cylinder.


At one point I was considering using it with A3 heads, they look so similar.


Oh, John, on the subject of you port matching the C60A to the 205 AFR's, Randy steered me to the CNC'd AFR 185's and the ports matched exactly. Mine was a new manifold that had been sitting on display for 50 years and a particularly clean casting with few if any casting flaws.

He pointed to the flow numbers on those heads, particularly the intakes that at .550 showed 296cfm, but the exhausts are exceptional also at 220.  Valves are 2.05/1.60. Combustion chamers 58cc but shaved mine down to 54cc. It seems to be a very good match.
He was still using Edelbrock Performers and thought he was giving something away because of the size of those runners, i.e., too big for his 331.
He was trying to keep me from going too big on the runners.

He knew I was running A3's on my Pantera with Webers. Those are 220cc ports v. 250 on the iron 4v heads and some say still too big on a 351.  I see the distraction. 185 v. 220 will make anyone pause and have concern for being too small.


On my previous set up, I had port matched a Blue Thunder 2x4 to my 68 302 4v heads. The result was a very nice respectable power band. The only issue with it was as predicted by Randy, #5 would run lean and you couldn't fix it.
Those heads had been very seriously ported and had 1.94/1.60 reduced stem valves installed.

Quote from: shelbydoug on January 21, 2025, 10:32:39 PMIf the Dual Dominator flows 1/2 of the carbs rating, why does it make more power then the Unicorn?

    Not to be cruel, and please don't take this the wrong way, but this and C.F.M. comparison efforts of the "plenum" style inductions to the "individual-runner" types just doesn't work; and truly prove as an attempted "apples to oranges" comparison.   :)

    Well, not without an awful lot of creative argument anyway. 

    Think of it like this:  You and your brother set off for Grandma's house for dinner, then find yourselves standing at a fork in the road.  Now the sign says that either path will take you to Grandma's house, so each of you choose to take a different route.  Upon your arrival several hours later, you find that your brother had arrived quite a period of time earlier than your self; so you inquire upon whether he had walked or ran and of the distance and difficulties he might have experienced along the way, this as compared to your trek.  In the end, you came to realize that although the signage was right, and that either path did get one to the same destination, the trip was not comparable!  ::)

     Scott.

Quote from: pbf777 on January 22, 2025, 12:01:15 PM

Quote from: shelbydoug on January 21, 2025, 10:32:39 PMIf the Dual Dominator flows 1/2 of the carbs rating, why does it make more power then the Unicorn?

    Not to be cruel, and please don't take this the wrong way, but this and C.F.M. comparison efforts of the "plenum" style inductions to the "individual-runner" types just doesn't work; and truly prove as an attempted "apples to oranges" comparison.   :)

    Well, not without an awful lot of creative argument anyway. 

    Think of it like this:  You and your brother set off for Grandma's house for dinner, then find yourselves standing at a fork in the road.  Now the sign says that either path will take you to Grandma's house, so each of you choose to take a different route.  Upon your arrival several hours later, you find that your brother had arrived quite a period of time earlier than your self; so you inquire upon whether he had walked or ran and of the distance and difficulties he might have experienced along the way, this as compared to your trek.  In the end, you came to realize that although the signage was right, and that either path did get one to the same destination, the trip was not comparable!  ::)

     Scott.

How do you know my effin' brother? He put you up to this right?  :-[

Quote from: shelbydoug on January 22, 2025, 12:34:34 PMHow do you know my effin' brother? He put you up to this right?  :-[

    And, let me guess.............he suggested which route whom should take............. ::)

    Scott.

Quote from: pbf777 on January 22, 2025, 01:34:34 PM

Quote from: shelbydoug on January 22, 2025, 12:34:34 PMHow do you know my effin' brother? He put you up to this right?  :-[

    And, let me guess.............he suggested which route whom should take............. ::)

    Scott.

The SOB! He knew that I was gullible.

The perceived advantage of the IR intake manifold is that you can adjust the mixture in each port with all of the variables that your carburetor allows you to adjust.

In a plenum style intake either 1x4 or 2x4 you can have extreme mixture variation between cylinders.

Particularly on a 1x4 intake manifold you have really long ports that go to (in the case of the SBF) cylinders #1,4,5 & 8. Where in order to get the same amount of volume to those ports velocity must be higher than in the shorter/tighter cylinders #2,3,6 & 7. Depending on how the intake manifold is configured cylinder variation costs you horsepower because you have to run the lean cylinders richer than the ideal mixture. A well designed 2x4 intake manifold that is balanced in port length and volume reduces some of this.

An IR intake allows you to adjust the mixture per cylinder (per se nothing is perfect) however you loose the beneficial effects of a balanced plenum. It is all compromise all of it.

Electronic engine management is better, however I prefer the dark arts.

There you go Scott, now you get better insight on exactly what I do not understand.


John

Quote from: JohnSlack on January 22, 2025, 03:19:20 PMThe perceived advantage of the IR intake manifold is that you can adjust the mixture in each port with all of the variables that your carburetor allows you to adjust.

In a plenum style intake either 1x4 or 2x4 you can have extreme mixture variation between cylinders.

Particularly on a 1x4 intake manifold you have really long ports that go to (in the case of the SBF) cylinders #1,4,5 & 8. Where in order to get the same amount of volume to those ports velocity must be higher than in the shorter/tighter cylinders #2,3,6 & 7. Depending on how the intake manifold is configured cylinder variation costs you horsepower because you have to run the lean cylinders richer than the ideal mixture. A well designed 2x4 intake manifold that is balanced in port length and volume reduces some of this.

An IR intake allows you to adjust the mixture per cylinder (per se nothing is perfect) however you loose the beneficial effects of a balanced plenum. It is all compromise all of it.

Electronic engine management is better, however I prefer the dark arts.

There you go Scott, now you get better insight on exactly what I do not understand.


John

Yes but it is also that you have a better runner configuration. Somewhere, someone determined that the optimum distance from intake valve to throttle plate opening was 4.5".

The Weber intakes on the 289's are right there as is the 351 Cleveland set up.


The question in my mind is, does the dual Dominator set up permit that intake runner length also?


In theory, you cannot have a more equal flow then equal length runners, with equal flow throttle "devices". The only variation you can have would be with the pumping capacity of each cylinder, and the intent is those to be equal as well.

With cylinder head ports CNC'd, the flow is equal as well.

Then it comes down to flow under the intake valve. Ford in fact understood that big valves got shrouded by the cylinder walls and realized that you could reduce the shrouding with a big valve by angling it away from the cylinder wall, enter the "Boss Cleveland" heads.

Now interesting to me, the current aftermarket Windsor heads largely are not taking advantage of reangling particularly the intake valve except for one. I think that is the Brodix, but I may be wrong on that.

The interesting thing that I am seeing though is that these aftermarket heads like the AFR's are making equal or better power then the canted valve Cleveland heads are. So maybe they already realized that angling the intake valve for unshrouding the intake flow was/is over rated?

You can't make the engine more equally distributed then that.


As far as not giving manufacturers certain credits, I noticed that the Edelbrock Performer RPM intakes have the carb plenums more centered then something like the C60A and more closely resemble the Unicorn's centering? I'm thinking I should give them credit for that thinking but also realize that they make the AFB/Carter/Edelbrock configuration carbs that are smaller then the Holleys are and make that possible without an offset distributor.

So I give them a credit for centering but take it away because they want you to buy their carbs for the manifold. I try to be fair but sometimes I admit that I do play favorites.

The Ford intakes we are discussing originated out of the Ford Racing Program so granted they likely just skipped over some steps and went directly to what they thought would be the top.

Why can't we use the Unicorn without an offset distributor by turning the regular Holleys sideways like the Dominator intake does? Ah, questions, questions? Randy baited you because you like to fish. I don't like fish. "Give me the facts". "Hit me with your best shot".

Henny Youngman used to talk about going to the doctor. "Doc, when I do this (he raises his hand) it hurts. "What should I do about it?" The doc replies, "don't do that". When I say that "I want a second opinion on something", the Doctor says, "ok, and you're ugly too". We all have unique lives.

Quote from: JohnSlack on January 22, 2025, 03:19:20 PMThe perceived advantage of the IR intake manifold is that you can adjust the mixture in each port with all of the variables that your carburetor allows you to adjust.

    True, but........... as stated previously, generally the practice for engines seeking peak performance is to strive for equality in actions among each the cylinders, therefore although individual tuning is a possible benefit, it is one that should not be necessary to capitalize upon in any major fashion.

    Rather, probably the initial intent of an I.R. manifold was more attuned to the ideology of the possible benefits of the resonance effect, or as popularly coined here "ram-tuning"; this providing for greater efficiency in cylinder filling utilizing the kinetic energy of the gas column created and retained.  :) 

Quote from: shelbydoug on January 23, 2025, 10:11:07 AMYes but it is also that you have a better runner configuration. Somewhere, someone determined that the optimum distance from intake valve to throttle plate opening was 4.5".

The Weber intakes on the 289's are right there as is the 351 Cleveland set up.

The question in my mind is, does the dual Dominator set up permit that intake runner length also?

    The "optimum" inlet tract length for the purpose of ram-tuning is dependent on a calculation involving engine R.P.M. as a major factor, as this is mostly a prospect based on a timing element, but of course also including a multitude of other considerations of lesser influential factors.  So, I believe with research, one would probably conclude that 4.5" is 'not' the "optimum" distance for any and all applications.  :-\

    As for the examples mentioned, I think this similarity is due more to packaging/fitment concerns, hence the repetitious similarities, this rather than anything ideal for gas-flow function.

    And in my opinion, it is this fitment issue that is probably where the T.A. Dual Dominator induction was compromised to the point of crippling it, as in order to get the whole "shebang" under that flat hood, the carburetors ended up just to close to the inlet valve; this creating just to much "signal" fluctuation for the carburetors to cope with.  :o     

    Oh, and generally the distance of consideration is more often that from the engines' inlet valve, but not to the "throttle plate" or butterfly, but rather to the top of the bell opening to atmosphere.  ;)

     Scott.

Quote from: pbf777 on January 23, 2025, 01:55:26 PM

Quote from: JohnSlack on January 22, 2025, 03:19:20 PMThe perceived advantage of the IR intake manifold is that you can adjust the mixture in each port with all of the variables that your carburetor allows you to adjust.

    True, but........... as stated previously, generally the practice for engines seeking peak performance is to strive for equality in actions among each the cylinders, therefore although individual tuning is a possible benefit, it is one that should not be necessary to capitalize upon in any major fashion.

    Rather, probably the initial intent of an I.R. manifold was more attuned to the ideology of the possible benefits of the resonance effect, or as popularly coined here "ram-tuning"; this providing for greater efficiency in cylinder filling utilizing the kinetic energy of the gas column created and retained.  :) 

Quote from: shelbydoug on January 23, 2025, 10:11:07 AMYes but it is also that you have a better runner configuration. Somewhere, someone determined that the optimum distance from intake valve to throttle plate opening was 4.5".

The Weber intakes on the 289's are right there as is the 351 Cleveland set up.

The question in my mind is, does the dual Dominator set up permit that intake runner length also?

    The "optimum" inlet tract length for the purpose of ram-tuning is dependent on a calculation involving engine R.P.M. as a major factor, as this is mostly a prospect based on a timing element, but of course also including a multitude of other considerations of lesser influential factors.  So, I believe with research, one would probably conclude that 4.5" is 'not' the "optimum" distance for any and all applications.  :-\

    As for the examples mentioned, I think this similarity is due more to packaging/fitment concerns, hence the repetitious similarities, this rather than anything ideal for gas-flow function.

    And in my opinion, it is this fitment issue that is probably where the T.A. Dual Dominator induction was compromised to the point of crippling it, as in order to get the whole "shebang" under that flat hood, the carburetors ended up just to close to the inlet valve; this creating just to much "signal" fluctuation for the carburetors to cope with.  :o     

    Oh, and generally the distance of consideration is more often that from the engines' inlet valve, but not to the "throttle plate" or butterfly, but rather to the top of the bell opening to atmosphere.  ;)

    Scott.

Tuned length, which is compromised/changed in the 2x4 intakes by the "tube" that extends from the bottom of the carburetor throttle plate to the lower intake plenum.


John

Quote from: JohnSlack on January 23, 2025, 02:45:12 PMTuned length, which is compromised/changed in the 2x4 intakes by the "tube" that extends from the bottom of the carburetor throttle plate to the lower intake plenum.

     To each his own in preferred definition; but,............in the endeavor for any significant "ram-effect" from the I.R. effort, this reversionary effect takes place when the higher than atmospheric air pressure column created when the inlet valve closes and the inertia retained in the in-motion gas column compresses and then rebounds, retained within the "tube" but in motion now headed upward (vertical stack) and exits into the atmosphere above the 'stacks', trailing with it out of the tube length is an excess volume that then creates a lesser than atmospheric pressure within the tube, that now "mother nature" (free atmosphere) races down the tube to normalize.

     The trick, and the reason there are different "ideal" lengths for this "tube", is in an effort to effectively time this reversion pressure pulse coming back down the stack on a following intake valve opening event.

     But none of this involves the actual throttle(s), as their function is exactly that, to "throttle" (disrupt) the air column which precludes this ram-tuning effect.  And the presents of an intake manifold consisting of a plenum promoting communication between port runners also disrupts and negates much of this value.    :)

     Scott. 

Well what I know about reversion in IR intake manifolds is that it is essentially caused by a late closing of the intake valve.

That being intentional in the design of the camshaft to push or pressurize atomized fuel in the center plenum of a 180´ intake manifold to aid loading of fuel into the next opening cylinder.

When you eliminate the common plenum, there is no where for that power pulse to go but up and out of the carb.
You can fix that to a degree with a camshaft timing change but not completely eliminate it by closing the intake valve sooner.

For me that was easier to understand by stating it as "valve overlap" although not completely accurate since the solution on the "Weber cam" was to reduce valve overlap to about 28°.

My experience with that is that solution reduced the fuel plume being pushed out of the carbs but the engine lost significant power of about 80 hp.

In the case of my Pantera, I discovered by accident that changing the velocity stacks from the stock length of about 2-1/2" to 5", kept the vapor plume within the stack and eliminated the spreading of the fuel issue.
That enabled me to keep the non-Weber cam so as John said, everything is a compromise and we are just trying to find the least power losses and lessen the tangential problems.

There is no room in a 69 B2 T/A car under the hood to find that kind of resolution. It just happens to work in the Pantera because of the size of the engine compartment.

I think that is somewhat to your thinking on the Dominators being just too close to the intake valves on the B2? Although lengthening that intake runner if possible to reduce reversion is sending me back on the long road to Grandma's house again AND exactly how long would that runner need to be to eliminate the reversion? 3 feet?

I stand by the 4.5". That isn't my number and may have come from Holman-Moody on the subject of the design of the Detomaso script Weber intake manifold? You may want to suggest that it is just co-incidental in the case of the 289 and 427 Weber intakes but I have come to not really believe in co-incidence.  Co-incidence to me is just the result of undiscovered intentions of someone or something else.

Quote from: shelbydoug on January 23, 2025, 07:50:02 PMWell what I know about reversion in IR intake manifolds is that it is essentially caused by a late closing of the intake valve.

You can fix that to a degree with a camshaft timing change but not completely eliminate it by closing the intake valve sooner.

For me that was easier to understand by stating it as "valve overlap" although not completely accurate since the solution on the "Weber cam" was to reduce valve overlap to about 28°.

    This could all be perhaps accurate when analyzing the situation at engine speeds below optimal, but also opening the valve too early compounds this issue too. But if this subject proves to be the capital concern it's more a statement that one chose the wrong camshaft.  :o

QuoteThat being intentional in the design of the camshaft to push or pressurize atomized fuel in the center plenum of a 180´ intake manifold to aid loading of fuel into the next opening cylinder.

    I don't think it was ever intentional (in engines relevant here) by design for one cylinder to be pushing fuel into another, that would incur greater complexity into the design elements than engineers would have wanted to approach, but it does take place to a degree regardless, but I would have to say only unintentionally. Rather the purpose for the 180° plenum design with it's alternating acquisition, in this case L-R-L-R-L-R.......,  was to separate cylinder draw from each volume for period to equalize and allow a sum of normalization in the atmospheres' pressure and turbulence this so as to encourage more equivalent charging of both air and fuel to each cylinder, also providing better signaling for carburetor function, etc..  Consider the plenum somewhat like the muffler in the exhaust system, it dampens the atmospheric pulsations and hence noise.  :)

QuoteI discovered by accident that changing the velocity stacks from the stock length of about 2-1/2" to 5", kept the vapor plume within the stack and eliminated the spreading of the fuel issue.

    This brings us back to the possible effects length has on the timing and placement of the air column in motion. ;)

QuoteI stand by the 4.5". You may want to suggest that it is just co-incidental................

     We need to differentiate what your stating as being positioned at 4.5" (from the inlet valve).  :-\
     
     Again, the throttles are not part of the plan in I.R. reversionary tactics, they just mess it all up;  the only thing that counts is the end of the tube!  The throttles can be (nearly) anywhere, the major effect in placement, beyond fitment concerns, and some directional air motion effects they create which need to be considered, is that generally the closer to cylinder head inlet valve they are, the quicker the engines' response to their movement will be; but still no effect on the other subject.   ;)

     Scott. 

https://www.youtube.com/watch?v=7nEGFfDH9e4

These are the iron GT40 heads and a Cobra single 4 high rise.

The C60A intake numbers have to be out there somewhere.

The head flow numbers are right around where Randy said they would be.

To those of you who are secretly following this thread, here is a link to an article about single four v. dual four inductions.

It explains in part how I arrived at this point, but not entirely.

It probably may also answer your question of how the Trans Am cars are involved in this discussion and comparisons...maybe? I find the description of the intake manifolds especially helpful to the novices amongst us.

It does not address at all the involvement of the Boss 302 or how it evolved into the Boss 302 in the discussion, but what do you want from a magazine article anyway, "everything, everywhere, all at once"?


I should also comment that I think it is significant that I am seeing different results in what my engine likes with the C60A T/A intake and carb sizes.
It may simply be that my combination varies enough from the mule engine that was tested in camshaft profile, engine displacement and induction ability of the cylinder heads I am using?

Where the article discusses a little difficulty in getting the jetting right on the 465 carbs which even after rejeting are running lean, is an indication that they are too small for that test engine, to me. The engine isn't getting the quantity of fuel it needs, and that is caused by the design of the T/A intake manifolds race capability.

There is a bit of an educated guess here since I am not artificially limiting the RPM range of the test due to concerns over breaking the engine? A 6,000 rpm limit is not really illustrating the true advantage of the T/A intake manifold, just showing that it has very decent "street type" manors.

As opposed to the much smaller capacity carburetors tested, I am showing good results with 2-600 1850 cfm vacuum secondary carbs and 2-715cfm  list 3300/3301BC/BD  carbs. Why? I don't know, just speculate on why they work well also.
It may be a much simpler answer in that the C60A may just run well on any combination? A bigger engine usually likes a bigger carburetor with some degree of predictability.


Anyway, check this out. To me it is a good read. I predict that it likely will create as many new questions as it does answering old ones? That really is the nature of the development process anyway. It is necessary to chase down ideas about how you thought things worked, then find you were completely wrong. But at least that saves time in ending theories created on false beliefs...to an extent.

https://www.motortrend.com/how-to/mdmp-1207-dual-quads-twin-win-or-double-trouble-part-2/


I'd LOVE to see a 351w build with the Price 2x4 intake. I haven't come across that anywhere but for me I'm fine with all this induction stuffed into a little 8.2 Ford Windsor'd head engine. Kind of like the "Hulk" busting out of too small of a shirt. Even if they are shiny aluminum AFR heads too. The open mouthed unblinking staring at car shows alone is worth it especially with the cold air induction built into the '68 Shelby hood.

It must be similar to what "Super Models" experience when they walk by in their micro-bikinis and guys start tripping and spilling their beers and coffee even in front of their own wives and girlfriends? Do you think that is cruel?  8)


Who says that this Forum is 98% just about Concourse cars? Not me.

Good luck.

Quote from: shelbydoug on January 29, 2025, 10:14:23 AMWhere the article discusses a little difficulty in getting the jetting right on the 465 carbs which even after rejeting are running lean, is an indication that they are too small............. The engine isn't getting the quantity of fuel it needs...........

    This suject of the "carburetor being to small and not delivering enough fuel", is often the thought, but stop and think about it; with the exception of the accelerator pump system the carburetor does not pump fuel into the engine, it's pushed in by the differential between the lower pressure venturi area vs. atmospheric pressure; and the smaller, more restrictive (C.F.M.) the carburetor might be, the lower the pressure (greater vacuum) value is presented and the stronger the siphoning effect is going to be.   :-\

    Aka, larger carburetors don't just have larger fuel jets because they potentially flow more air and yes would potentially need to flow more fuel commensurately, but also because often this differential pressure (signal) is less prominent and therefore the fuel delivery is less effective, so larger (less restrictive) fueling jetting offsets some of this also.   ;) 

    As far as for the 465's not providing the better performance, well in my experience, that has generally been the result, this to the point that I just don't prefer, nor recommend them.  :)

    Scott.

Quote from: pbf777 on February 24, 2025, 01:00:53 PM

Quote from: shelbydoug on January 29, 2025, 10:14:23 AMWhere the article discusses a little difficulty in getting the jetting right on the 465 carbs which even after rejeting are running lean, is an indication that they are too small............. The engine isn't getting the quantity of fuel it needs...........

    This suject of the "carburetor being to small and not delivering enough fuel", is often the thought, but stop and think about it; with the exception of the accelerator pump system the carburetor does not pump fuel into the engine, it's pushed in by the differential between the lower pressure venturi area vs. atmospheric pressure; and the smaller, more restrictive (C.F.M.) the carburetor might be, the lower the pressure (greater vacuum) value is presented and the stronger the siphoning effect is going to be.   :-\

    Aka, larger carburetors don't just have larger fuel jets because they potentially flow more air and yes would potentially need to flow more fuel commensurately, but also because often this differential pressure (signal) is less prominent and therefore the fuel delivery is less effective, so larger (less restrictive) fueling jetting offsets some of this also.   ;) 

    As far as for the 465's not providing the better performance, well in my experience, that has generally been the result, this to the point that I just don't prefer, nor recommend them.  :)

    Scott.

As far as for the 465's not providing the better performance, well in my experience, that has generally been the result, this to the point that I just don't prefer, nor recommend them.  :)

Scott,
I think that if someone wanted to run 465 Holley carburetors that was knowledgeable about circuits they could get the carburetor to function just fine.


John

Quote from: JohnSlack on February 24, 2025, 01:39:33 PMI think that if someone wanted to run 465 Holley carburetors that was knowledgeable about circuits they could get the carburetor to function just fine.

    No disagreement here, but if not a required for some reason, why start with a carburetor that one already knows is going to require greater effort than perhaps something else?  :-\

    Scott.

I view some things, like these induction combinations, like playing with Legos.

We just take various shapes and assemble them in all possible combinations until we arrive at one with the best results. Sometimes the more outrageous, the better the solution?

Some would call that the empirical method? That is being very diplomatic.  ::)


The way some of you speak of this suggests that there is no carburetor that is too big or none too small? That just makes no logical sense to me whatsoever but this has just turned into a food fight with little or no point anyway?


I would go with copying the actual results as best I can to those who were the most successful in racing. Not to the extent so much as when "Grumpy Jenkins" would pull out his dipstick and hold it up to the sunlight to look for something, and seemingly almost everyone else would also, but looking for the failures that seemed so obvious that I didn't want to go down that road as well?

So then why not have a disagreement? It does seem entertaining to a point? Maybe it is just Quantum Physics and it is the creation of an equal but opposite electron instantaneously created at the opposite end of the Universe, then extinguishes itself instantaneously? Makes as much sense to me?


Some of these combinations are just going to work better then others and one of the keys is this C60A intake. It does seem to have this zenomorph capability and considering the unpredictability of the various carburation combinations, that's as good of an explanation as anything at this point?


I can't help but think though that there is an actual correlation between engine size and carburetor size? Someone could probably even write a simple equation there with a pretty much direct proportion predicting outcome? An outrageously abstract thought isn't it? I probably need shock therapy or some serious medications...but that's another subject all together for another day.

Quote from: pbf777 on February 24, 2025, 01:00:53 PM

Quote from: shelbydoug on January 29, 2025, 10:14:23 AMWhere the article discusses a little difficulty in getting the jetting right on the 465 carbs which even after rejeting are running lean, is an indication that they are too small............. The engine isn't getting the quantity of fuel it needs...........

    This suject of the "carburetor being to small and not delivering enough fuel", is often the thought, but stop and think about it; with the exception of the accelerator pump system the carburetor does not pump fuel into the engine, it's pushed in by the differential between the lower pressure venturi area vs. atmospheric pressure; and the smaller, more restrictive (C.F.M.) the carburetor might be, the lower the pressure (greater vacuum) value is presented and the stronger the siphoning effect is going to be.  :-\

    Aka, larger carburetors don't just have larger fuel jets because they potentially flow more air and yes would potentially need to flow more fuel commensurately, but also because often this differential pressure (signal) is less prominent and therefore the fuel delivery is less effective, so larger (less restrictive) fueling jetting offsets some of this also.  ;) 

    As far as for the 465's not providing the better performance, well in my experience, that has generally been the result, this to the point that I just don't prefer, nor recommend them.  :)

    Scott.

As far as for the 465's not providing the better performance, well in my experience, that has generally been the result, this to the point that I just don't prefer, nor recommend them.  :)

Scott,
I think that if someone wanted to run 465 Holley carburetors that was knowledgeable about circuits they could get the carburetor to function just fine.


John

Quote from: shelbydoug on February 24, 2025, 04:34:11 PMI view some things, like these induction combinations, like playing with Legos.

We just take various shapes and assemble them in all possible combinations until we arrive at one with the best results. Sometimes the more outrageous, the better the solution?

Some would call that the empirical method? That is being very diplomatic.  ::)


The way some of you speak of this suggests that there is no carburetor that is too big or none too small? That just makes no logical sense to me whatsoever but this has just turned into a food fight with little or no point anyway?


I would go with copying the actual results as best I can to those who were the most successful in racing. Not to the extent so much as when "Grumpy Jenkins" would pull out his dipstick and hold it up to the sunlight to look for something, and seemingly almost everyone else would also, but looking for the failures that seemed so obvious that I didn't want to go down that road as well?

So then why not have a disagreement? It does seem entertaining to a point? Maybe it is just Quantum Physics and it is the creation of an equal but opposite electron instantaneously created at the opposite end of the Universe, then extinguishes itself instantaneously? Makes as much sense to me?


Some of these combinations are just going to work better then others and one of the keys is this C60A intake. It does seem to have this zenomorph capability and considering the unpredictability of the various carburation combinations, that's as good of an explanation as anything at this point?


I can't help but think though that there is an actual correlation between engine size and carburetor size? Someone could probably even write a simple equation there with a pretty much direct proportion predicting outcome? An outrageously abstract thought isn't it? I probably need shock therapy or some serious medications...but that's another subject all together for another day.

Well I for one don't have anything else to add to this particular discussion.

Quote from: JohnSlack on February 24, 2025, 06:48:07 PMWell I for one don't have anything else to add to this particular discussion.

    Awh com'on, jump in, the water's fine! Besides...........you just did!  ::)

    Scott.

Quote from: pbf777 on February 24, 2025, 07:22:41 PM

Quote from: JohnSlack on February 24, 2025, 06:48:07 PMWell I for one don't have anything else to add to this particular discussion.

    Awh com'on, jump in, the water's fine! Besides...........you just did!  ::)

    Scott.

Too cold here. Jump in the water in Miami.