for drivability and simplicity, the '66 Quadrajet manifold and a 800cfm quadrajet. for power an Edelbrock B262 or stock dual quad and a pair of AFB's or Edelbrocks you can do the 3 deuces, and if you do, go with 2GC's, which means you need a 4 bolt manifold, and just so ya know the easy to get Offy ****s. It's adequate but doesn't make power.
Thanks for all the info guys. I like the 3x2 setup gives the engine a nice old school look that I am looking for and the 2x4 would give me the performance I need. I really need to think about this one before I commit to one. There would only be a difference of 250 cfm from the 3x2 to the 2x4. Would this be a noticable difference in performance?
Is the engine stock? If you have worked the **** out of it compared to stock would be a BIG factor. Doc. Deuces, that was my exact same first thought as well!!
since im using it as a parts chacer im using a gear drive 2x2 u fab tunnel ram,,,,im going with the holley 4412 nascar late model claimer carbs......there 500 cfm so its 1000 like a dominater,,and basically with a nail you can pull along side wt a tanker and it wont mint ,,anything you bolt too it will be fine........sept an offy the just plain ****
With a stock engine and triples you'll mostly be running on the center carb (if it's set up correctly) which will mean the engine will run smooth and the torque will be as good as if not better than a stock 401 and torque is what Buicks are best known for. If you get a 401 running right on a two barrel (with 2 more standing by if needed) you'll burn rubber until you let off.
agreed. i have a 3x2 set up with progressive linkage on my 56 roadmaster with a 401 in it. and granted the thing is worked to the balls, gigantic cam and all that. the thing runs great and when u open it up u def feel the other 2 carbs open. on the highway i get around 14 to 17 miles to the gallon as well pretty good for a car its size with a big motor in it. with the progressive linkage you can feel in the pedel travel when your opening up the other two cars, so when on the highway cruzing right just off the mid carb does great. good luck with you motor.
YES!!! running two 600 afb's and and weiand intake and she's really happy when the second carb starts to open...
Any fuel system is a compromise. What is best depends on what criteria you wish to maximize. Least cost and ease of installion: (1) Single four (2) 2 x 4 (3) 3 x 2 Looks (1) Either 2 x 4 or 3 x 2 (2) Single 4 Driveability (1) Single 4 (2) 2 x 4 (3) 3 x 2 Economy (1) 2 x 4 (2) Single 4 (3) 3 x 2 Power (1) 2 x 4 (2) Single 4 (5) 3 x 2 Jon.
In this case the Single 4, and especially in the case of the Quadrajet manifold, it gets better economy than the 2x4. The Quadrajet also is neck and neck with the stock 2x4 for power. And in the case of an Offenhauser manifold it stomps all over it.
Sometimes there are major differences from system to system. Sometimes the differences are only a couple of percent. In Zman's examples, I would certainly agree that the Q-Jet could get better economy, and would be very close, but somewhat less than the 2 x 4 in power. Note that the 3 x 2 comes in last in all categories except looks. Jon.
As this thread is about Nailheads, lets stick to them. The Quadrajet is neck and neck with the stock 2x4 in power, less than the Edelbrock B262, and MORE than the Offenhauser.
I'm going to have to disagree on the power and economy. I've not run a 3x2 but I have run several types of 4 barrel intake (stock, QJet and Gessler) and three types of 2x4 (stock, Gessler and Edelbrock B262). As the owner and editor of www.buickstreet.com I have heard a lot of stories and got a lot of feedback on what's working and what's not. The Offenhauser intake is notoriously bad but a 401 sipping from a 2 barrel would have to be the most economical, then again sipping from a single 4 barrel would also use the same amount of fuel and in fact sipping from a 4 barrel in a dual quad arrangement would also net the exact same fuel economy. The difference is not in what uses less fuel because travelling at 30mph down the road will use as much fuel in all cases. It's when you boot it that the economy really starts to vary. Without a doubt the big dual 4 barrels will guzzle fuel like there's no tomorrow when you plant your foot because in almost all cases two 4 barrel carbs will pour much more fuel into the engine than would ever be required. The stock 4 barrel would fair a bit better if it's tuned well but a quadrajet will only pull as much air flow as they secondaries will allow through so I would guess that the Quadrajet on a stock Q-Jet intake would use the least amount of fuel on throttle than all the combos (except the Offy). A triple carb setup will pour fuel into the engine regardless of the requirements as well as they are mechanically opened by your foot. For all around general economy and street use power a Quadrajet intake with an 750 or 800cfm (I've run both - even an 850 Edelbrock Q-Jet) Quadrajet carb is by far your best bet unless your only concern is economy (in which case I doubt you'd be buying and driving a 400 cubic inch engine). If all you are concerned about is economy then a 3x2 with the single two barrel working 95% of the time (and the throttle) will be your best bet. In my opinion a low or medium rise dual quad looks "right". Here's a picture of mine with stock intake and dual 650cfm Carters. and here is a "no brakes" take off using the same... Here is a normal intake (for carter) on the right in black and a larger secondary (1966 only) on the left in green. Here's a picture of the two ported by Greg Gessler intakes I had done... For interest, here are the flow charts for before and after stock 2x4 intake... and here's the before and after (porting) flow chart for the single 4 barrel... While I was there I found this neat pic I made to illustrate how to instantly identify the "bump" in an 800cfm Quadrajet. If anyone wants any more close ups of the porting that Greg does let me know and I'll post them. Hope this helps someone.
You seem to not grasp some rudimentary theories and practices of induction. Now I've been a member of the Yahoo Nailhead list for as long as it's been around. 10 years or so. First off find a single 2 barrel manifold for the 401/425 otherwise your single 2 barrel theory doesn't hold water. You can either have a 3 deuce set up running progressive and keep your foot out of it. Then you can have the Quadrajet running and keep your foot out of it, it only runs on two barrels. Then you have the dual quad running progressive, keep your foot out of it, ony two barrels. They should all get the same mileage, but it doesn't work that way. The manifolds flow very differently. We'll throw the Gesslers out for the economy portion as they flow better but lose velocity at low to mids which effects economy. The most common by far 3x2 manifold is the Offenhauser, it ****s, it doesn't deliver in any real way, economy or power. It's the bottom rung. The dual quad (stock) running progressive gets better mileage when driven timidly, but will you? The Quadrajet does better than the squarebore manifolds by virtue of the carb and manifold. Though not much better than the AFB on the squarebore. Those are the facts. Years of experience and a lot of research.
Don't get me wrong, I understand that air speed is important and no I didn't take into account the inefficiencies of running a center 2 barrel carb in a 3 x 2 set up. I agree, the stock 2 barrel intake and carbs would be the best for economy. I was just trying to lend some of my personal experience. You have much more of course. A tad harsh.
Careful about discussing the cfm differences: a two-bbl carb is rated on a different scale (inches of mercury) than a 4bbl carb. For instance, the old Mopar 440-6 pack intakes were rated at 1350cfm: 500 each for the outboard carbs, and 350 for the inboard. That does not mean it was the same as running a 1350cfm 4bbl. After doing the math, the conversion factor is 1.4. 2bbl CFM divided by 1.4 = 4bbl CFM 4bbl CFM x 1.4 = 2bbl CFM So 1350cfm of 2bbl carbs equals a 964cfm 4bbl. For simplicity, go with a quadrajet or AFB 4-bbl on a stock intake. For performance, go with the factory 2x4 intake, unless you can find the Edelbrock 2x4. The factory 2x4 intakes are a lot more common, and generally cheaper. -Brad
Not to be a ****, but the guy HAS RUN Gessler-ported intakes and stock intakes, which makes me reasonably sure he's also run a bunch of other factory intakes in big cars and hot rods. "I've done it" trumps a whole lot of "I've researched it on the interweb and have belonged to a website for 10 years." Running the stock, aftermarket and modified versions of the intakes he has tells me he's got a pretty good understanding of the rudimentary theories and practices of induction. -Brad
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