Well it’s been awhile since I’ve been here. And despite what my screen name says, I’m no longer a “CollegeKid”. I recently stumbled onto a complete 1962 Cadillac 390 engine about 10 minutes from my house complete with Hydramatic. It was pulled because it was ticking and getting tired, but was still being driven until the owner decided on an LS swap. So naturally since that’s been one of my dream engines for a future hot rod project I had to buy it. In the future whenever I get around to actually being able to build it I want to probably do a multi carb setup. I like the looks of the old 3x2 and 4x2 Edelbrock manifolds, but they’re expensive as hell I’ve seen. The 3x2 Offenhauser is an option as well and it helps that you can buy new ones now. My questions are does anyone have any experience with these manifolds and how they perform vs each other? How do they compare to the factory 3x2 setups or the 2x4 Eldorado manifolds?
Factory’s were heavy on bigger cars that did not go to aluminum as they didn’t care like Chevrolets and Pontiac’s. You know they worked with the carburetor that was stock usually Carter WCFB’s and stock camshafts. Others here will tell you which ones are best.
The offenhauser is a nice manifold design and is the best looking 3x2 in my opinion, I have this one for sale with nice rebuilt 97’s if you’re interested send me a PM.
Rochester's were considered a better carb at the time and were the replacements for Carters on the earlier mid 50's Cadillacs. I believe the stock dual quads of earlier ones were Carters but by 62 I don't. The Rochester's took up more room. As a single carb I prefer the Rochester and ran engines with them very trouble free but do not know with todays fuel. The CarbKing here knows way more than the rest of us and can chime in. If you find a dual quad aftermarker your best bet would be AFB style. Any way you go you will be still looking over $1000 for good usable parts to start with. I know I have way over that with my dual quads for my Y-Block 6 years ago and parts more available for them.
Eldorado /Sevilles in 1957 was the last year for factory dual quads , the 57 dual quad has the larger bolt pattern for AFB carbs and earlier years take the WCFB carbs , 58 to 60 went to 3X2 factory option with 59/60 having larger secondary carbs, the 61 to 62 went back to regular 4V factory intakes
Cadillac's first modern multiple carb set-up was 1955, which was a dual-quad with a pair of Rochester 4GC carbs. These were the "square" (3 3/4 x 3 7/8) pattern. Cadillac did have multiple carbs on their V-12 and V-16 engines in the 1930's, so the 1955 is not their first rodeo. In 1956, Cadillac changed the carburetor vendor to Carter, for a pair of WCFB carbs, still with the square pattern. In 1957, there is an early and late set with the early rectangular pattern, and larger WCFB's. Perhaps due to influence from the Pontiac tripower, and Oldsmobile J-2, Cadillac discontinued the dual quads, and offered a tripower in 1958. The 1958 unit used three of the small base Rochester 2 barrels. In 1959, the manifold was revised to accept 2 of the larger carbs for the dumpers. End of history, to your question: In 45 years of specializing in multiple carb set-ups, we have NEVER done an aftermarket tripower or quad two-barrel set-up for Cadillac; so I have no personal experience with these. With this history, I cannot believe the aftermarket units remotely compared to the original for performance (on Cadillac engines). (Opinion) if you are looking for performance, then dual quads are the way to go. For verification of this opinion, check with the Allard folks running Cad engines in vintage racing. Have set up several of these, virtually always the late 1957 factory unit with WCFB carbs. Have done a couple of the early (square) WCFB and 4GC setups for the Allards as well. Have NEVER had an Allard owner even ask about tripower. We have done a couple of dual two-barrels for the Allard folks. A company called Detroit Racing produced a dual two-barrel manifold prior to the introduction of the 4-barrel. Have done a number of factory tripowers, ALWAYS for the number-matching folks that had no care about performance. If you are looking for eye-candy, with less performance; then tripower (would suggest factory), or maybe the quad deuces. Original manifold casting numbers are listed here: https://www.thecarburetorshop.com/Multiplecarbmanifolds.htm Original carburetor numbers (1955 and 1956) are listed here: https://www.thecarburetorshop.com/Kcadillac1.htm And (1957) here: https://www.thecarburetorshop.com/Kcadillac2.htm You can make other than factory carburetors work, but anything other than factory WILL required modifications. One modification that SHOULD be made to the factory carbs is to replace the "throttle sensitive" automatic choke with a conventional automatic choke (or manual, if you prefer). If I were looking to build a performance dual quad engine today, I would find a factory manifold, either 1956 or 1957, and modify it to accept Carter AFB carbs. I would then find a pair of IDENTICAL genuine Carter AFB carbs designed for early 1960's Caddy (the year doesn't really matter, as long as the carbs are identical), and do minor calibration modifications as needed. If the Cadillac AFB's prove difficult, then, in order, Pontiac, Buick, and Chrysler AFB's could all be modified, but the modifications would be more difficult and expensive. I would not suggest Chevrolet AFB's, or the genuine Carter Comp Series AFB's with Chevrolet calibrations, or the modern imitation AFB's with Chevrolet calibrations; unless you are independently wealthy, and don't care about remaining so. Jon.
Thanks again CarbKing. Your information is as always “right on” I continue to use original carburetors instead of modern replacements as often as I can.
Originals were calibrated specifically for the engine by carburetion engineers. Unless the engine is highly modified, very difficult to compete with originals. Some folks complain about the price of originals, but often the "initial savings" by starting with the wrong carbs is quickly dissolved with modification parts costs, not to mention the aggravation. And I still love your avatar. My first car was a 1956 with a 292, same color as yours. Jon.
So you would say the original factory dual quads would have outperformed the factory three twos if they left the dual quads as an option for the 390s?
Like I posted earlier, we have NEVER done a 3x2 for the Allard folks that compete in vintage racing. And if the originals (WCFB's) for the 365 were replaced with AFB's for the 390, even better. The above is opinion based on almost 50 years of doing performance carburetors; but I have never personally nor do I know of a test where someone did a back to back of these on a dyno. EDIT: a related test would be the folks at Pontiac responsible for the early Super Duty race program concluded that 3x2 was no competition for either a single 4-barrel or dual 4-barrels. Pontiac continued to sell the 3x2 as eye candy (and it sold well); but paid Carter to sabotage the AFB so the single four engine would not outrun the more expensive tripower engine Jon
Yes - I have posted this on several forums, including this one, a number of times. 573-392-7378 (9-12, 1-4 Mon-Tues central time). EDIT: Here is a hint: https://www.thecarburetorshop.com/Hotidle3.jpg Jon.
I’m still kind of dumb when it comes to carbs, what am I looking at in the picture of those three pieces?
The easy and least expensive route sounds like, keep your factory four barrel intake with a vintage Cad' AFB. Cheap, reliable, easy to tune. The rod is the eye candy, few will notice the multiple carb's. Just my opinion.
Ok you guys are going to think I’m a bonehead , but I was just out looking at my engine and I do have a Carter AFB not a Rochester like I thought originally. Duh guess I need to pay better attention.
The genuine Carter AFB's are excellent carburetors. Your initial post stated you might like to try multi-carburetion, and asked about performance. If performance is your goal: Assuming the AFB you have is original to the engine, rebuilt, it will provide excellent performance, and possible more than any multiple-carb set-up, depending on YOUR skill as a tuner. If you (or your tuner) is well-versed in the science of selecting multiple carburetors, and the art of tuning multiple carburetors; some additional performance could be found in a dual quad set-up. If eye-candy is your goal: Beauty of the engine is in the eyes of the beholder. You being the owner of the engine, your opinion (or possibly that of your spouse) is/are the only opinion(s) that count. Jon
Thank you for the insight CarbKing. Well I’ve got some time to plan. I still can’t afford to do much with the 390 other than dream at the moment. Like the original post says I scooped it up about 10 minutes from my house. Dumb luck really. As to carbs I do think I still want to do multiple carbs for the extra looks, but now I have some deciding to do. I’ve always thought a bunch of Strombergs on a hot rod look sweet, but if they perform worse than a factory four barrel then are they worth it? Dual four barrels look pretty cool too and from what I’m hearing would probably perform better if set up correctly. So I need to decide, find another Carter AFB to match the one I have and then a 57 intake, or go with the eye candy Strombergs.
The Best dual quad manifold for a Cad 390 is the Weiand WCA 408. These will fit AFB's and will flow better than the earlier Weiand manifold for the "square" pattern carbs. They're not easy to find and will not be cheap when you do find one; no speed equipment for early Cads is cheap anymore. I'm running one on the 390 in my '40; works well so far with great throttle response...
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