65-67 Dual Quads

[Drew Pojedinec]

Who would buy a shelf cam?
Comp XE256H is pretty close.
Not sure where you got the idea it would be an industrial engine...
If someone wanted a cruiser or wanted to do something like power tour, this type of cam would be my suggestion.

Cam profile isn't as simple a matter as you make it seem. Your comment about it wearing the same is incorrect. No one can actually predict that with the info given. Too many other factors.

The same goes with the comments about power. The benefit of multicarb setups isn't always just airflow potential.
For a street car I would 100% of the time choose 6 or 8 venturi over 2 or 4.

[shelbydoug]

Who would buy a shelf cam?
Comp XE256H is pretty close.
Not sure where you got the idea it would be an industrial engine...
If someone wanted a cruiser or wanted to do something like power tour, this type of cam would be my suggestion.

Cam profile isn't as simple a matter as you make it seem. Your comment about it wearing the same is incorrect. No one can actually predict that with the info given. Too many other factors.

The same goes with the comments about power. The benefit of multicarb setups isn't always just airflow potential.
For a street car I would 100% of the time choose 6 or 8 venturi over 2 or 4.

Ah. We have reached a point of disagreement. I'll leave it at that.

You have your experiences. I have my 50 plus years of them. Sounds irreconcilable to me?
No hard feelings though.

[mygt350]

Ok, after LOT of feedback, I am focused on the C6ZZ-6B068-A manifold with the miss-stamped firing order between the flanges that mounted the two Holley 460 carbs.This intake will allow use of the chrome air cleaners or the cast finned air cleaner base and top.
Am interested in purchasing complete unit or the correct pieces.

[shelbydoug]

That is a "Trans-Am" racing manifold. It is made for 715 cfm carbs.

Using 460cfm carbs on it is somewhat of a mismatch. On a 289 it is probably worth about 30 hp over the FoMoCo dual quads with the big carbs but will loose something like 30 lb-ft of torque off of idle where you need it for a "street car". Because of it's race characteristics, you need "gears" with it and it is not a good match with an automatic transmission with a 2.30 first gear unless you run 4.11 or more.


The C60A and the SHELBY lettered aftermarket version are all the same off of the same molds with just different ID "drop ins".

You wind up with whatever you can find that is available. I am running the C60A intake. Currently with 1850's but have run the BC-BD 427 carbs which are 715's or 725's depending on if you use Ford's rating sytem of Holleys's.


By comparison to the FoMoCo intake, they are large runners flowing around 285cfm each. That is a stock Boss 302 vicinity. Randy could guide you better then me on this but stock 289 heads are at best 210-220 cfm. Race ported, depending on the porter to around 230-240.

The factory 289 race cars were running the GT40 iron heads which is what the T/A manifolds were intended for and flow comparable numbers to the intake.


These manifolds were made before tunnel rams existed. Besides their greater flow potential, at wide open throttle, they are equal flow runners resembling a tunnel ram but tied together with a common twin plenum, so it is really two manifold designs mated together. It's really a hybrid that doesn't exist anywhere else.

The FoMoCo is definitely torquier with not as much top end as the T/A. The T/A manifolds are all about top end. That is what they are for.

I ran that also and found that just gasket matching the intake runners to the heads a noticeable amount was gained. For an automatic transmissioned car, it is a better match. There the smaller carbs might be ok?

[Drew Pojedinec]

I think you are missing what he is doing. 

[shelbydoug]

I think you are missing what he is doing. 

More like I am missing his point? I'm just trying to add my knowledge to what I've already been through but as had been said, "it is the journey and not the destination".

It definitely will keep you busy and hold your attention while you draw your own conclusions and realize your own misconceptions. Journey on.

I never would have imagined before I started that the best carbs to run on a small block would have been the BC-BD's?

Plus commenting here keeps me out of the garage for a while and gives me time to recall where I put my large ratcheting internal lock ring pliers..as well as staying away from ATTEMPTING TO date 'Super Models' and avoiding expensive divorce lawyers or court restraining orders?

Fantasies have their benefits.

[Drew Pojedinec]

If I recall, I told you 715s are a somewhat better venturi to bore relationship to any other size.

You told me I was wrong. Later you installed them 😂  (50 years of experience and all)

Martin's goal here is to collect original induction systems. Once I realized who the handle referred to, it made more sense. He is only really into as delivered stuff for display. As such, using 1850s or 3300s or how it runs isn't the endgame.
I got him a 3x2 setup, now on the hunt for 2x4 gear.

[shelbydoug]

If I recall, I told you 715s are a somewhat better venturi to bore relationship to any other size.

You told me I was wrong. Later you installed them 😂  (50 years of experience and all)

Martin's goal here is to collect original induction systems. Once I realized who the handle referred to, it made more sense. He is only really into as delivered stuff for display. As such, using 1850s or 3300s or how it runs isn't the endgame.
I got him a 3x2 setup, now on the hunt for 2x4 gear.

I make mistakes. If I said that, I apologize, you are right about the BC-BD carbs. They just seem better at every point.

This is a forum for sharing information and learning. Making mistakes is part of learning.


You are somewhat of a new comer here. It is rare someone like you will share their knowledge. A person like myself must take that new learned knowledge and go back and review what I've already done, correct my mistakes and often revise my view of it.

I do appreciate you sharing your knowledge, no question, but I need to review how I can apply it. In the past this type of info seemed proprietary with no one willing to share so what I've learned and what I've made mistakes on is on my shoulders  but for 50 years has kept me interested and maybe that interest has kept me alive? Who knows? Who cares?
The BC-BD's are new to me. Not something I was exposed to 50 years ago.

I would just add or maybe more correctly reemphasize that it isn't just one component that is being dealt with here, it is an entire package that effects the induction...including the exhaust.

So just installing another carb is rarely a self supporting solution. There are some applications where there will be a conflict. Reading the original salesmen's selling points and accepting that as Gospel from the "catalog" is not a technical solution.

Talking about induction systems and if someone will be happy or not with them is like recommending a camshaft profile that you love, but when the recomendee installs it, absolutely hates it. I don't recommend cams any more. I should have learned from that and applied that to inductions also?


It is just my view and obviously others differ of opinion but to me multiple carburation is for going faster by the means of making more power. Sometimes that seems like attempting to be an alchemist and trying to turn lead into gold.
The Ford "trans-am" intakes may be the best manifolds ever made for the small block Ford, but the intent was for maximum power at racing speeds.

They may in fact have many streetable factors but it is unlikely that there was any consideration of streetability to them in their design.


Another factor that is significant now is that these systems are ancient solutions with old technology. SOME changes in technology available now, not then, change the results you can get from old concept.


In my own defense, I would blame differences of opinion sometimes on the lack of my applicable terminology, not someone else but in many cases I'm still stuck with old terms, descriptions or explanations of why something doesn't work as well as it is expected to.

I appreciate your input and it is influential on my solutions but it is very evident that my criteria varies significantly from others. So with that lack of terminology, I can't always clearly explain.


Also, it is a clear and an ever present issue of the written word not illustrating the tone that is intended. If I seemed to be lecturing, chastising, or the expert, etc., that is not my intent and I apologize to all it concerns but it is probably a very good idea that when you go to shoot skeet with that shotgun that you wear a nice pad on your shoulder? Sometimes the elders have helpful reminders?

Maybe old geezers like me should be quiet and let everyone figure it out for themselves? That might be the solution. Point well taken.


The phrase of "beware of false profits" does bother me occasionally though. Better just to say "brothers and sisters, I feel your pain" or just keep it all to myself and yet some still cry out for help.


No question that any multiple induction system is a great display item but how long can anyone resist "trying" one that they have been playing with on their display shelf? Sometimes a hint on where to start helps on something that is more complicated then it first appears? Sometimes you just have to go for it?

[Wedgeman]

Doug...have you ever known anyone running one of those TA 2x4 setups on a small block stroker ( 331, 347, 363 ) with a pair of AFR or Trickflow heads?" just wondering....Thanks....

[shelbydoug]

Yes. That is my setup. 347. AFR 185 heads. Comp Cams solid lifter cam. JBA headers. Richmond (Doug Nash) 5 speed.

[jerry merrill]

I also have a 347 with AFR 185 heads with that T/A manifold. It currently has twin 390 carbs and a big comp roller cam and it is the best running small block I have ever had. It had 600''s and then 460's but would foul plugs. I don't claim to be an expert but for the last 6 years it has been flawless with no bogging and amazing performance. i followed the advice of Car Craft magazine article from about ten years ago that tested this manifold with various carbs and found the 390's worked the best. For an all out race car you might use larger carbs but for anything short of that smaller might work better. Never had it on a dyno but it has to be north of 400 hp.

[TA Coupe]

I think this may be the article you are referring to:

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

This is part 1 using the earlier over the counter 2x4:

https://www.motortrend.com/how-to/mdmp-1206-dual-quad-carburetors-testing-part-1/?cx_navSource=related-right

Here's a huge discussion on multiple carbs. Better grab a beer or two to read the whole thing:

http://garage.grumpysperformance.com/index.php?threads/dual-quads.444/

I'm going to post a screenshot about how the CFM of carburetors is rated in a 2x4 configuration. I don't know if it is real accurate but I have something here that I've been trying to find for years that says basically the same thing. It is part of the discussion I posted a link to above.
I ran 2x4s every day for more than 15 years on my 302W with an automatic with straight linkage so I know it's a very streetable combination. I've run both 390s and 465s and currently run 465s on my boss 302 shortblock with 2bbl closed chamber heads that was made to use a Windsor intake and I use the TA intake.

         Roy

[shelbydoug]

Thanks for posting Roy. 

I've personally never been able to feel what a 10hp difference is but I really think the Motor Trend conclusions are disqualifying.


The most significant factor being limiting an engine with a "flat out, bonsai suicide engine intake" to only 6,000 rpm. To me that immediately shows a misunderstanding of the application by of all people, "enthusiast technical editors".
Publishing deadlines can be a bitch. It all sounded like a good idea in the Monday morning meeting but that deadline comes up all too fast and you can't hold the presses forever?

I'll leave it at that. I'm not going to write a book which brings me to the second "article" or maybe more correctly an attempt at writing an Encyclopedia for the Internet. That one does not include all possible factors. It doesn't test the applications with a real driver, in a real car under ideal conditions or consider the effects of timely Solar flairs (<sarcastic remark here).


It all comes back to what anyone wants to go through experiencing personally how these set ups effect and are interpreted.


As far as running an automatic, personally, with an automatic, I'd go with a 6R80. Why not? We are mixing new tech with old and we all have our own personal favorite mixes. I like Cosmo's.

I once had seven in a row, but I'm not really sure now if it was only three and I was so blitzed that I thought it was seven? There is no tape to review so it has to stay as I remember it?

How much horsepower was I making? I don't know, I passed out on the couch? (<more sarcasm...please help me stop!)


Now see all the excitement ANYONE is missing by limiting themselves to ONLY building displays? 

[TA Coupe]

The 6000 RPM limit was probably the limit the owner of the car/engine was willing to take it to or where the power started to fall off due to the small cam. I used to take mine to 8 grand all the time and even to 8200 a few times but I had a lot more cam.
Who's Earl😉

        Roy

[shelbydoug]

The 6000 RPM limit was probably the limit the owner of the car/engine was willing to take it to or where the power started to fall off due to the small cam. I used to take mine to 8 grand all the time and even to 8200 a few times but I had a lot more cam.
Who's Earl😉

        Roy

OK. Then what is the validity of that "test" besides none at all?