Tunning Dual Carbs

[shelbydoug]

Those heads were shaved .030 by the original race engine builder (Danbury Competition) but the ports and pockets were left alone. They show 630 @ 600, so why look for more?

I hope this isn't suggesting 630 CFM @ .600" lift. That is Blue Thunder Big Block Thor head intake flow.

It isn't suggesting anything. It is stating the facts from the flow bench. It's actually at .630 lift.

Your flow bench is defective

That's ok...so am I. 

[gt350hr]

   Doug,
      Your post says 630 it should be 330 IMHO. NO  Cleveland head on this planet will go over 400. 630 is beyond the best Pro Stock heads out there at the moment. Joe's good but not that good LOL.
    Randy

[shelbydoug]

   Doug,
      Your post says 630 it should be 330 IMHO. NO  Cleveland head on this planet will go over 400. 630 is beyond the best Pro Stock heads out there at the moment. Joe's good but not that good LOL.
    Randy

Correct. 330. I already admitted I was defective? So? 

...oh...and not that I can actually USE that kind of flow? Never said that 

[gt350hr]

 No problem.
It's also  important to mention that different dual quad intakes have their own "quirks". There are some significant tuning differences between the early Ford 289 dual quad and the later T/A - SHELBY letterd version. The early manifold is not as finicky on tuning. Guess how I know.
    Randy

[shelbydoug]

No problem.
It's also  important to mention that different dual quad intakes have their own "quirks". There are some significant tuning differences between the early Ford 289 dual quad and the later T/A - SHELBY letterd version. The early manifold is not as finicky on tuning. Guess how I know.
    Randy

I would think there was no consideration on the T/A manifold for any idle quality considerations at all? IF the engine happens to idle with a .650 lift, 300 something duration cam to begin with, that would be shocking.

"It's the manifold. Yep, let's blame the manifold!"

I'd like to see a side by side comparison of those two manifolds on a dyno with a "street engine".

As per our discussions I'm really shocked that the new aftermarket windsor heads are getting these kind of flow numbers with these small ports. Maybe the better manifold IS the street manifold?

Also, I can swear that this Blue Thunder version I've got has had it's runners finagled with from the original? Somethin' a little funky with it? 

[gt350hr]

    Doug , In order,

     No manifold except the lousy "fuel economy" ancient Edelbrock stuff is designed for idle quality. That is carburetor calibration/tuning.

     Certain manifolds/ spacers/cams etc. , make tuning for a good idle a challenge to say the least

     About 15-20 hp on a semi stock street engine with a significant loss of low rpm torque. ( until 3,000 rpm)

     The street manifold ( Blue Thunder ) is a restriction on a head that flows over 220cfm . The T/A manifold is best with 240-270 cfm and will not support 300+ even with substantial porting.

     It may be funky but not a bread winner in the flow department over the original Ford manifold.  No measurable performance difference "out of the box".

     The above is purely from my experience and yours may vary.
      Randy

[shelbydoug]

As you once pointed out the iron GT40 heads were at best 250cfm and Joey pointed out that the AFR heads were at 296 at .550. That is better then iron Boss 302 heads.

So my rational is that I am putting them on for less weight, my iron heads crapped out and anything I get over and above that is icing on the cake.

You put 800hp in a Mustang and it's still a 12 second car.


You do bring up the subject of intake flow on these 2x4 intakes though which is why a while ago I asked you if you had experience with the SHELBY 2x4 BOSS 302T/A manifold? The runners do look bigger on them and I KNOW you messed with the Tunnel Ports which definitely are bigger.

To me, all of those SB T/A manifolds look like the same core/runners, just changed to mate with the intended ports on the heads, that being where the restrictions come in?

Aside from the port mismatch, I think physically the Boss 302 will bolt up to a Windsor head. That's what I was thinking when I asked you about that. Are you going to say that one only flows 250 as well?

See. I get these radical thoughts that just peculate up out of nowhere like the volcano in Hawaii. Once it starts, you can't stop it and the magma runs all over everything.


You talk about restrictive intakes. How about carbs? No one ever considered that a 48ida with a 42mm choke is restrictive on a 289 (that's 300cfm), but it is or that there is no way a 289 can use a 715 Holley. I'm ok with all of that.  Don't tell the carbs though, ok? They get very upset sometimes. 

How's a 300cfm carb restrictive on a head that at best flows 250? Oh no...stop the magma please.


Complaints are all relative though. Any way I look at it, I'm over 400hp on the dyno and starting out at best at 250, I'm doing ok.

[gt350hr]

     Doug ,
        I've run about 70% of the dual quad intakes produced for the Boss 302. It's easier to say which ones I haven't run most of which are owned by Gus Tarrab.  The dual quad Cross Boss ( for regular Holleys)` , the ''variable runner" dual dominator , and a "box" plenum dual quad are about the only ones.
   Near 300 cfm flow in a wedge versus a Boss head is a very different situation and doesn't compare well with the same being said for the tunnel port.  "Flow" is a number and by itself doesn't relate to the efficiency of the port. That is a common mistake of those who only pay attention to flow. Same for Webers. They are designed to be run as "IR" or one barrel (isolated) for each cylinder. IF yo put Webers on a dual plane ( or common plenum) manifold you would be looking at almost 2,000 CFM because each port "could" draw from any one of the eight venturis.

   I put 800 hp in a Mustang and it would NOT run in the 12s unless it was the HALF mile , or it was running 6.95x14 blue streaks! You might but not me.

   Boss intakes need larger volume runners than does a 289 , pure and simple. H&M cobbled up some intakes ( with allot of welding) to fit a Boss head , but they were poor on performance.

[1109RWHP]

The ports on the Trick Flow heads are smaller than a Boss head so the intake needed some epoxy work to make it match. Plus I think Ray Charles ported it at one time.

[1109RWHP]

[gt350hr]

   Your manifold was a "predecessor" of the SHELBY lettered Boss intake. This was a common thing H&M did with Buddy Barr.  Manifold designs that Ford chose not to use or a project was cancelled, often got an H&M logo or Holman Moody spelled out and sent to them to sell.  This saved them ALL of the development costs ( Ford already paid that) and gave them finished parts  in the $30 a piece range , delivered. Most sold for over $150 through H&M so the profits were excellent.

[shelbydoug]

   Your manifold was a "predecessor" of the SHELBY lettered Boss intake. This was a common thing H&M did with Buddy Barr.  Manifold designs that Ford chose nit to use or a project was cancelled, often got an H&M logo or Holman Moody spelled out and sent to them to sell.  This saved them ALL of the development costs ( Ford already paid that) and gave them finished parts  in the $30 a piece range , delivered. Most sold for over $150 through H&M so the profits were excellent.

Tony Carey tells me he never paid more then $50 for a manifold. I asked him for a T/A and he said $2500 BUT he'll take trades. 

Yes, I'm aware of the different aspects of an IR vs. a 180 intake. My point was about the flow numbers also.

2400cfm is what a set of Webers will flow. You need to adjust that for the size of the chokes. That number was for a 42mm which is what the Shelby Team cars were credited with running.

The only way to answer many of these questions scientifically is side by side on the same engine with the various combinations. Since in this day and age that's about as likely as me cloning a Tyrannosaurus rex. So the next best thing is to pick someone's brain while they can still remember before it all fades into the mist?

Guess who won out as the source? 


So basically what you are telling me now, again, is that PROBABLY the best match for me is the T/A with a wedge head. Then another $4500 to replace the hood that the engine just sucked in?

I gotta' plan this out better? 


GREAT PICTURES! THANKS!


What effect does changing the firing order to the 351 order have on the manifold?
 

[gt350hr]

    2400 cfm is the "capability" of the carbs. If you put a low meter on each individual "throat" you will find less than 100 cfm per cylinder
actually" flowing. ( more like 75) Reversion , lack of a common plenum , etc hurt the flow . BUT if the carb was any smaller , it would hurt horsepower. Ford realized in '62 that 48s were too small for high rpm use at Indy for the 255 pushrod engine and switched to 58s. 48s on a 427 was like a 750 single four , so some manifolds were made for 58s though there weren't enough carbs to go around. 58s on a SOHC was a loser too. Not enough cfm because of the lack of a common plenum for all the cylinders to draw from.  IR sucks , literally. Your Pantera would go faster with 58s too. Just about the right size. Modern sprint car guys now use 3" butterflies ( or more) on their fuel injection systems and make 900 hp.
  Two Webers on a "common plenum , non IR" manifold would be what Ford was trying to do with the Autolite Inline. I plan on switching my 331 to a Vic Jr single four to see how much faster it is than the old school dual quad.
   Changing the firing order is not a big deal power wise on a dual plane intake.
    Randy

[shelbydoug]

    2400 cfm is the "capability" of the carbs. If you put a low meter on each individual "throat" you will find less than 100 cfm per cylinder
actually" flowing. ( more like 75) Reversion , lack of a common plenum , etc hurt the flow . BUT if the carb was any smaller , it would hurt horsepower. Ford realized in '62 that 48s were too small for high rpm use at Indy for the 255 pushrod engine and switched to 58s. 48s on a 427 was like a 750 single four , so some manifolds were made for 58s though there weren't enough carbs to go around. 58s on a SOHC was a loser too. Not enough cfm because of the lack of a common plenum for all the cylinders to draw from.  IR sucks , literally. Your Pantera would go faster with 58s too. Just about the right size. Modern sprint car guys now use 3" butterflies ( or more) on their fuel injection systems and make 900 hp.
  Two Webers on a "common plenum , non IR" manifold would be what Ford was trying to do with the Autolite Inline. I plan on switching my 331 to a Vic Jr single four to see how much faster it is than the old school dual quad.
   Changing the firing order is not a big deal power wise on a dual plane intake.
    Randy

Go faster? I need to hold on now!

I know of only 4 sets of 58's. Bob Gingold has one of them still in the original wood case, all serial numbered concurrently. They came in what looks like a display case all lined in velvet like a Proof Coin set does from South Africa.

The "Pantera" manifolds are "tuned" for 51mm. Lots of graphs with all sorts of bright colors all circle and intersect right at that point BUT the consideration is for a 6,800rpm max.

What actually flows through an engine, I personally don't know.

According to one of the formulas, my A3 heads would need to see 11,000 rpm for the engine to be able to pump that much air with 357 cubes. Whenever I see Joey he asks about them. All I know is "they work good".  They work better then the iron heads. That's what I tell him. Hey. They were $400 bucks. How could I turn them down? No doubt he regrets that sale? 



12 seconds 1/4, 197 @ 6,800 in 5th is at my limit if I'm lucky. Depends is making some really nice designer type adult diapers. Reasonably priced to.

Hey Mike Cook went 9.6 at 130 somethingin Gary Hall's GTS Pantera by just changing to 5.36 gears. No fancy Webers, just a 4779 Holley.



I gave up on drag racing because the tire shake hurts my neck. Blurry vision from it is too spooky. I can't see where I'm going. I need a tracer light that I just point at. Detached retinas. Attached rectum. The smell from all of that smoking rubber turns my stomach too? Plus I'm sensitive to the spectators. They give me the finger and one guy "mooned" me? How insulting?

At least if Jungle Jane would flash me just once! That would help.


At some point flow numbers do mean something, probably a lot? I have to remember that not only am I the driver, I'm the pit crew and the sponsor.

At one time the Dodgers wanted to talk to me because I threw 100mph. That's fine. Do you know how fast the ball comes back when the batter hits it? Don't ask. You don't want to know. Your eyes can't focus fast enough to see it but if it gets you, you likely won't remember a thing...IF you survive that is? 


Aluminum heads. They're just there to save weight an polish up with Mothers.

So far, I haven't found anything that sounds like Webers or pulls out of high speed turns like them. It is easy to show on a dyno how EFI eight stack pulls better on the average but it doesn't pull harder in key spots.

Plus, it doesn't throw flames through the stacks in the dark at cold start up. That one always draws crowds.

[gt350hr]

      Here's a curve Doug. IF you had a two inch tall "box" made to bolt onto your Weber manifold you could run two Webers and make more power than you do now with four. The ability for all eight cylinders to "feed" off of a common area makes a huge difference.