Interesting dyno test of ancient dual quads

Nicks Garage in Canada used a heathy 451 low deck stroker. With an Edelbrock RPM intake and Holley carburetor the engine made 536 hp. With a dual quad intake from a 1959 383 and 2 Carters the engine made 30hp less.......but the engine looks ABSOLUTELY BEAUTIFUL with this set up. The iron dual carb setup did have carb spacers and Nick is not done with tuning- hopefully will be in a later video. This engine he utilized is very powerful and I say the ancient dual quad manifold on a 350-425 hp low deck engine would not be the restriction it is on a 500 plus hp unit. I wonder if the iron factory Chrysler dual quad manifolds are as good or better than what Offenhauser made?

https://www.youtube.com/watch?v=4wYHE3BlxlQ&t=1124s

Dual quads are cool as hell, no doubt about it. Thinking about going that way with my '66, since racing doesn't really fit the schedule any more.

When you consider the old manifold was designed for an engine 70 CI smaller, it's not too shabby at all.

Is the Offy the manifold that was/ is run on the 343hp 383 in stock or S/S? I would imagine the iron unit that came on the 62-3 B- bodies was the same intake as the 58-59 low decks.

Yes they are! Its tech from a time that when you wanted more power you HAD to add another carburetor. The Chevy 409 , 331-354 Hemis, early Chevy small blocks- just a nice looking pleasant experience when opening the hood.

I cant answer your question but the tech at the time is apparent. The factory dual quads by Chrysler- the Offenhauser units and a manifold made by Weiand all have the same design. A single plane large plenum. The Edelbrock D66 for the 273 and the Edelbrock CH28 for the 440 are familiar dual plane designs. Offenhauser dual quad manifolds were used to make roots blower intake manifolds (and not for just mopars) by many companies. The open plenum design worked well for this and machining/welding/ converting one was cheaper than casting one from scratch.

i use a ch28 with two 600 edelbrocks on a 440. i think it's the best street induction system i've ever used. very smooth power and very low maintenance. far less trouble than the stock single 4bbl set-up on my '69 r/t. i was a die hard 6pak guy for decades but for half the price and no major power loss i'm happy. too many myths about multi carbs. the key is to match the carbs up and use a good intake. the edelbrock should be far superior to factory iron on a RB engine. B engine guys don't have a good manifold choice. if those older single planes have to be used pay attention to the torque curve. peak power doesn't drive the car.

Ancient what do you mean ancient


Nick does some interesting stuff, I watch him every once in a while, and especially like his Dyno tests on stock/almost stock engines.

Assuming the carb and single 4 barrel manifold had been optimized and he was still dialing in the dual quads the final results might be a little closer. Part of the reason for the spacers might have been the hole size on the manifold were smaller than the throttle plates on the AFBs it was set up with, but who knows.

“…..the key is to match the carbs up and use a good intake…….”

Lewtot is absolutely right, but additionally you need to take the time and really dial everything in, both jetting and timing. Every combination is going to want something just a little different.

I ran the same low deck intake on a reasonably stock 68 375HP 440 I had in my 57 Dodge (the old B1 spacer plates worked well to mate it to the RB). Around the same time, I did a pair of carbs for a friends’ 426 wedge he had put an Edelbrock Dual Plane intake on. After everything was dialed in I really didn’t see that much seat of the pants performance difference between the two. The one thing I did note was that the factory single plane was a lot more cold blooded until the engine reached operating temperature (the B1 plates eliminated the heat crossover passage).


A couple years ago I changed out the dual plane Tri-Power for single plane dual quads on the 354 in the 57 Plymouth. After dialing in the dual quads I picked up power across the rpm range. I lost 3 MPG at highway speed but the performance gain and general drivability made it a worthwhile swap.


TPDQ by M Patterson, on Flickr

It's hard to argue with the eye appeal of more than one carb.

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i like this

While not quite as blingy as dual quads n a big block

Dual carbs for my flathead six.

cool! i like that vintage stuff.

Mike P wrote "Ancient what do you mean ancient?"

I know what you mean but remember- that intake is from a 1959 383. Thats 63 years old!!!!!

I ran that intake with two Edelbrock 500s on two different 440s. ABSOLTELY AWSEOME. RB guys are lucky to have the CH28. Why do I say that? Well LA small block guys- the 340 360 guys are lacking options. The Offfenhauser dual quad for the small block is that old single plane large plenum design and is actually for the 273- Small ports and not enough meat to port out to 340 360 size. The Edelbrock D66 is a true dual plane dual quad....but for the 273. Additionally its rare and fetches $$$$$$$$$. There is the Modman. It is for the 340-360 head and looks fantastic. But is not a low RPM drivable manifold.
Low deck guys have only the 50s design of dual quads available. I personally would be willing to sacrifice some power under the curve for that dual quad look provided by those "ancient" dual quad designs.

Here is a Modman: http://indyheads.com/images/30.cat2014.pdf

“…….Thats 63 years old!!!!!.......”

Hell I wish I was only 63 years old.


I was thinking back on my comment about the single plane B intake I used to have being cold blooded.

One of the things I started using on some cars that were either cold blooded and/or had a healthy cam are MSD boxes which seem to be a pretty good band aid for both conditions. I suspect it would have also helped the dual quad B intake on the 440 in the 57 Dodge.

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looking at the video it appears they are using the factory small venturi/throttle bore stock carbs. i think those would be ideal for that manifold. the secondary throttle bores on all the edelbrock afb's are too large for a stock unmodified manifold.

I believe Nick in the video will be jetting those two Carters and doing another dyno run.

Hopefully, he sync's them too

I am a fun of multi carbed anything. Hence why I have 3 six pack set ups (a 340, 383 and 440), a magnesium Hemi cross ram, a 413 cross ram project next and a dual Dominator tunnel ram on my Hemi street/strip car.

".......I am a fun of multi carbed anything......."

I tend to agree.

37 eng by M Patterson, on Flickr


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[quote=Mike P]“…….Thats 63 years old!!!!!.......”

Hell I wish I was only 63 years old. ]


ME TOO !!!!

i would like to use a pair of Thermo-Quads on a CH28 if i could find a cheap intake.
i have a 446 with a 590 cammed, edelbrock head'ed engine sitting here i could put into my charger, or try a T-Quad log ram intake for my humpback.

you would really have to cut one up to do thermoquads. not opposed to it but work. i do believe from a performance stand point the 1407 is probably ideal and would max out the as cast manifold. i would like to try a pair of 1407's one of these days.

He must not know anything about the early AFB air flow ratings, those stock small bolt pattern AFB barely flowed 400 CFM originally each.
I wish he had stated the actual carb #s instead of ASSUMING that they were 625 CFM Carter AFB
I've owned and race several cars with stock dual quad sets up like that one years ago
We never made the fuel systems good enough to feed the motors more fuel than they needed, they always show the plugs being dead lean at WOT WE didn't know what we hadn't learn yet

those stock carbs were nowhere near 625cfm each.

if i had to give an educated guess, i would say they "might" be around 395cfm each.

To me it looks like someone from marketing made a conceptual sketch of an interchangeable top manifold using a magic marker on a Mcdonalds napkin while they were eating lunch. Then somebody picked up the napkin and sent it off to the pattern shop. Nobody including Indy wants to tell you how it compares to any other intakes including their own. Can it putt around town or is it an 8500rpm race only piece? It would be killer if it actually fits somewhere between the Edelbrock dual planes and the Indy tub style intakes. I know there are a few running in NSS but I haven't seen any comparison with any of the other manifolds that are available. Have there been any comparative tests posted or published? If anybody has experience with these please post results and thoughts.