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Technical 3x2 or 2x4 carb setup ?

Discussion in 'The Hokey Ass Message Board' started by Wizard1926, Sep 14, 2023.

  1. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Thinking of changing up the look of my 26 Tudor. This is just a cruiser for around town cruise nights ect.

    Looking at 3x2 or 2x4 carb setups

    It's a mild built 1st gen 350, punched 30, mild RV cam. Nothing radical.

    Have an air gap intake with 650 holley on it now.

    So very interested in hearing your opinions and advice on what your running and why.

    dana barlow and daniel wilson like this.
  2. skooch
    Joined: Feb 7, 2007
    Posts: 229


    Both are time proven to give a performance boost, what makes your heart go pitter pat when you see it?
    dana barlow, hrm2k and 2OLD2FAST like this.
  3. WC145
    Joined: Jul 21, 2012
    Posts: 151

    from Maine

    Three deuces got the look if you ask me, but I'm biased. I think they're pretty easy to live with and not to difficult to get dialed in.
  4. Paul
    Joined: Aug 29, 2002
    Posts: 16,363


    I practically built my current project around the original J2 tri-power setup on the 371 Olds,
    then for no real good reason changed to a dual four setup..
    probably influenced by Ivo's T in Hot Rod Girl movie

    they both perform great but I do prefer the dual four for looks, tune ability (parts availability) and performance


  5. jnaki
    Joined: Jan 1, 2015
    Posts: 9,168


    upload_2023-9-14_10-8-54.png 3 x 2 on a 348 impala

    We ran the stock 3 x 2 on our 58 Impala. it gave us 280 hp at full throttle. but, around town, the center two barrel ran all of the time. for gas usage, that was great. When I stepped on the throttle, it was gentle and not forcing anything. But, the power of the 348 motor was available when and if I needed it. the center two barrel is the ultimate for normal daily street driving and road trips on highways.

    My friend started with the 4 barrel on his 57 283 motor. It was a great running motor and again, ran the two barrel until the other side was necessary on a full throttle escapade. So, again, great gas mileage, good power for all normal daily driving to school, cruising around and on open highways. But, if and when the other two barrel was necessary, it came alive. 4 full barrels.

    But, he had a deal working for him. Another friend did not like his dual 4 barrel carb set up on a Corvette. He was not worried about gas mileage, but drivability around town. 90% of everyday driving was with a four barrels, when he stomped on the throttle, now all 8 barrels were in action and the Corvette took off. Yes, we drove that 60 Corvette around and it did have a lot of power. At the time, any lightweight fiberglass bodied sporty car with a powerful motor was intimidating with the combination of power and weight.

    So, we traded the dual 4 barrel manifold/carb set up for the single 4 barrel carb set up. The cost was minimal as the trade off was that we did the work and the older friend was now happy with a single 4 barrel carb for everyday driving. Acceleration was perfect, and there was still plenty of power for the Corvette to accelerate and feel like a fast sporty car.

    My friend’s dual 4 barrel set up was now adding some extra horsepower to his 283 with a cam and headers set up. When we finished, it was so much more powerful. We also installed a complete 4 speed and Positraction third member to round out the street performer. What about the drivability of the dual quads?

    Although the two barrels on each carb were functioning like a full 4 barrel carb, it did use up more gasoline. But when the throttle was pushed down, the effect of another 4 barrel carb came into play. the surge was outstanding. Now, I had a functioning 2 barrel carb on my 348 with the additional 4 barrel power when I needed it. my friend had a 4 barrel running all of the time and had an additional 4 barrel power on hand for any extra encounters.


    For everyday street driving, I stay with the factory vacuum linkage process. It never failed and came on when I needed it. The progressive linkage I put on was ok for the all out dragstrip acceleration day/night events, but just awful for the street, without the other two carbs coming into play. So, I stayed with the vacuum linkage for the rest of the days I owned the 58 Impala.

    For normal everyday driving and long distance road trips, a fully functioning center two barrel carb will work the best and will make easy driving in any traffic. For strictly racing, the dual quad set up is probably better and it will be up to you as to how your use your hot rod or cruiser. I would get a three two barrel carb set up over a dual quad set up.


    When my brother and I were in the process of getting our 283 Isky Cam/Jahns Pistons motor running, we were offered a choice of dual quads (our first choice) versus a 6 carb Stromberg set up. The local speed shop owner said both are good set ups. For the drags, the 6 carbs would be better for more power. But, it did run on the center 2 two barrel carbs until the progressive linkage came on with the other 4 carburetors kicking in full throttle mode. Or the whole 6 carb set up could be linked all together at once.

    I would go with the three two barrel set up for the street’s everyday driving. YRMV
  6. tubman
    Joined: May 16, 2007
    Posts: 6,874


    Since it's a '26 Tudor, 3-2's say "Hot Rod" to me; 2-4's? Not so much.
    daniel wilson and hrm2k like this.
  7. hrm2k
    Joined: Oct 2, 2007
    Posts: 4,800


    The OP has left out much of the important part of a 3 deuce setup. I went with Stromberg 48’s on a mild 350 . You could do the same with Carters or Rochesters, pick your poison. I was tickled with the performance and not much else is traditional as Stromberg. It took some screwing around with the linkage but was worth every minute. This is how it looked
  8. manyolcars
    Joined: Mar 30, 2001
    Posts: 9,158


    I've always thought of 3 deuces as street driven traditional hotrods and 2 4s as racecar/muscle car stuff. Two totally different types of cars.
    Last edited: Sep 14, 2023
    High test 63 and Paul like this.
  9. Jmountainjr
    Joined: Dec 29, 2006
    Posts: 1,646


    I guess the first consideration is how much do you enjoy tuning on carbs? The 650 CFM carb that you have now is the ideal size and pretty much a "set it and forget it" deal. Multiple carb setups usually require some playing around with jet sizes and power valves ( if equipped). The three two barrel setups vary a bunch on carb size used. The Holley 94s and Stromberg 97s are in the 155 to 175 CFM range depending on specifics. Rochester 2GCs are in the 250 to 450 CFM range depending on specifics. If you are building this yourself, the biggest hurdle is finding matched cores to build the carbs. Many variables under the same model. And when comparing two barrel to four barrel CFM ratings you need to equalize them due to the different amount of vacuum used in the standard. To convert two barrel CFM ratings into "four barrel speak" devide by 1.414. So, my six Holley 94s at about 155 CFM each is not 930 CFM in four barrel comparison. It's only about 660 CFM. The biggest decision on the three twos after deciding what carbs is how you want to run them linkage wise because it changes how the carbs are built. You can run all three carbs all the time using straight linkage, or run on the center carb (typically) and then dump in the end carbs at some point using progressive linkage. When doing that the idle circuits are blocked off. I happen to think it's easier to tune straight linkage. But that's typically the minority position. As to four barrels, I think your best bet are two small CFM carbs with vacuum or air valve controlled secondaries. And you have the same linkage considerations - straight or progressive. Again, I prefer straight. If you want the multi carbs, but really don't like to play with them, there are a few shops, or an experienced friend, that can get you very, very close out of the box. Good luck.
    hrm2k likes this.
  10. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    I really like the look of 3x2, but hear they can be a bit finicky???
  11. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Nice looking ride !! I will agree the 3x2 setup looks better for old school.
  12. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Thanks. Been doing alot of reading up on the tuning ability of the the 3x2 vs 2x4 setups. Like you stated, the 2x4 seems easier to tune in.
  13. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Incredible information!!!
    Thank you !
    jnaki likes this.
  14. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Man, that's a sweat ride !
    Thanks for your advice !
    hrm2k likes this.
  15. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Thank you for the great write up and information. I will be purchasing a complete new setup which ever way I go. 3x2 or 2x4. Intake, cards, linkage etc. I see Holley is offering a 3x2 setup. Anyone try one ?
    hrm2k likes this.
  16. hrm2k
    Joined: Oct 2, 2007
    Posts: 4,800


    Now that we have confused the shit out of you. :D
    You might also think about 4 deuces or maybe 6.
    This is my new build setup….screams hot rod


    Thanks Mark !!
  17. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,718


    I'm of the school that says if it isn't broke don't spend 1000 bucks trying to change it just to impress a few mouth breathers.
    Now if it just doesn't have that kick in the seat of the pants performance you are looking for head on, go for the multi carbs. I started out with the 2x4 Corvette intake with matching carbs on the 327 in my 57 Chevy panel truck that had the internals to use them 327 with 12.5 Jahn's pistions, Engle solid lifter cam an 202 heads. That truck was quick but drank gas like a barfly drinking 2 buck happy hour schooners. Swapped the 4 barrel off my T bucket to the panel and put the Corvette intake on the 283 in my T. With the 098 cam and powerpack heads it ran pretty good but as others said, took some tuning on an all too regular basis. That was part of life when I was 27, Run the valves and adjust the carbs and go drive.

    Your call but if it is just looks you are thinking about rather than actual performance gains it may take rethinking.
    MCjim and hrm2k like this.
  18. Back when I built my hotrodA roadster, I was able to snag a 348 3x2 setup. As I was putting them on a 350, with a mild cam, they were perfect. They had the correct, no idle adjustments on the front and rear, correct inlets, and just needed the linkage. Great with running just the center carb.
    Nowadays you can get the replacement bases and the small base 2G/2GC carbs are still out there, just takes some looking. My vote is easy.

    Tow Truck Tom, dana barlow and hrm2k like this.
  19. jimmy six
    Joined: Mar 21, 2006
    Posts: 14,659

    jimmy six

    2-4’s . . . . they look like they are meant for “business” and not show. If you put them on and are cruising down the road about 70 and open them….you will know what every guy who has them knows…..there is no other sound like hearing dual quads sing no matter what engine they are on.
    I run mine progressively just like a the 245 and 270 hp SBC’s and saw no milage different than the single 4 barrel when driving normally. 3-2’s are the same if progressive like they were on 348’s and 389 Pontiacs.
    Last edited: Sep 14, 2023
  20. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    Thanks Mark ! I like your comments about being confused. Yep, lots of options to think about. At least no one said old school injection
    hrm2k likes this.
  21. Wizard1926
    Joined: Jun 17, 2023
    Posts: 98


    You are prob right. The Airgap intake and single carb works great and dependable.
    Just Gary and Chavezk21 like this.
  22. de-fenders
    Joined: Jul 10, 2006
    Posts: 692


  23. Ive got 2x4s on the 350 in my 33 pickup and then a 3x2 setup on a 327 in my grandparents 55 Chevy. Both are fantastic setups and both engines run hard. Cant really complain about either of them. The dual quads on the 33 have not been really messed with in 30 years. The tri power has been a little more finicky but mainly because the carbs were chrome plated years ago. Biggest thing to consider is what heads are on your 350? If you have a set of later vortec style with the intake bolts straight up and down then a 3x2 intake is harder to find. If you have older style heads then no issues.
    hrm2k likes this.
  24. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,810

    427 sleeper

    F.W.I.W... I'm just about burnt out on a 3x2 intake on anything but a J-2 Old's or a Poncho. I like 2x4's for the looks and the performance, plus they're easier to get dialed in, atleast to me they are. :rolleyes: YMMV
    loudbang and MCjim like this.
  25. The Rochester GM tri power set up is easy as can be. The center carb has the idle circuit , the end carbs need to seal air when closed and not drip fuel. Run progressive linkage. They are easy to rebuild too.

    The hardest part of that is finding the right stuff that hasn’t been molested, canabalized, fixed or otherwise fucked with too bad.
    There’s some brand new reproduction stuff out there, read the reviews.
  26. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 2,810

    427 sleeper

    This is why I won't do a 3x2 anymore, unless carbking restores the carb's to factory perfect!
  27. Here's my answer. Just picked this up at swap meet last Saturday. 20230910_150405.jpg
  28. '51 Norm
    Joined: Dec 6, 2010
    Posts: 824

    '51 Norm
    from colorado

    I'm doing 2X4 this time 'cuz my last one was 3X2 and I've never had dual quads. Time will tell.
    hrm2k and dana barlow like this.
  29. dana barlow
    Joined: May 30, 2006
    Posts: 5,102

    dana barlow
    from Miami Fla.
    1. Y-blocks

    I've always liked,more then one carb looks,but do admit my one 4bbl did run the best.
    Even so,the cool factor is way up with more then one carb,so the first set up I had,I really liked was 2x4s in 1959 n 60,after a guy offered what I thought too much $,at the time,I sold my 2x4. Used my 4bbl for a time,and then made my own intake for 6x2=Was a bit much for my Ford Y 292. Next homemade intake was 4x2,by cutting up a driveshaft. It works better then the 6x2. I think its max cool,even though a PITA . 001 (4).JPG
    Tow Truck Tom, hrm2k and Paul like this.
  30. I'm a 2x4 guy and a firm believer in 1 to 1 linkage on them, 2x4's just make a statement of all business. Three out of four of my cars are currently running dual quads and the fourth will be too as soon as I get the engine together.
    On the way home tonight from a cruise night I put my automatic in full manual mode and let it sing, sure sounds great at rpm.
    Even the deer come out to see dual quads

    20230914_190704.jpg 20230914_190656.jpg

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