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Technical Dual Quad illusion?

Discussion in 'The Hokey Ass Message Board' started by KahunaKat, Dec 15, 2019.

  1. KahunaKat
    Joined: Sep 30, 2015
    Posts: 111

    from Texas

    Has anyone ever took a dual quad intake and ran it off one four barrel carb and a second one that was none functioning giving the illusion of having a dual carb setup? o_O

    Merry Christmas and Happy New Year, Everybody!
  2. Inked Monkey
    Joined: Apr 19, 2011
    Posts: 1,834

    Inked Monkey

    I think that would starve one side of the motor
    loudbang likes this.
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 50,965


    I don't know about doing what you said, but using progressive linkage on a dual quad setup is relatively common.

    If the engine has dual quads just for looks, and you never want to go fast, then sure, you could leave one disconnected. Have fun!
    scrap metal 48 likes this.
  4. poncho catalina
    Joined: Sep 22, 2008
    Posts: 81

    poncho catalina
    from summit il

    I don't know about 2 4bls but I a guy that had a tri power that only the middle carb functioned
    scrap metal 48 likes this.

  5. I have done it a few times, mostly on show cars that are only driven onto and off of trailers.
    Tunnel rams work the best for this. I saw a unique setup once, it was built on a tunnel ram and consisted of two holleys on top with no throttle plates and a third small carb mounted inside of the upper plenum. A lot of work just for the "look". I built a 6x2 setup where only one center carb was operational. Built a lot of 3x2 setups where only the center carb flowed air (Holley and Rochesters).
    I polished two Holley 600's for a show car where the secondaries were disconnected (looked like 660's)
  6. LM14
    Joined: Dec 18, 2009
    Posts: 1,937

    Member Emeritus
    from Iowa

    Have seen a lot of flatheads that were only running one of 2 or 3 carbs. If it's possible is basically determined by the design of the intake manifold and plenum area.

    wvenfield likes this.
  7. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,831

    Johnny Gee
    from Downey, Ca

    Depends on style of intake. That said, yes it can be done.
    wvenfield and flatout51 like this.
  8. flatout51
    Joined: Jul 26, 2006
    Posts: 1,030


    I agree with Johnny. If it's an open plenum or not.
    Sent from my SM-G977U using The H.A.M.B. mobile app
    dearjose likes this.
  9. KoolKat-57
    Joined: Feb 22, 2010
    Posts: 3,043

    from Dublin, OH

    The dual quads on my Hemi are setup as progressive.
    Runs off the rear carb until I hit it.
    Both carbs have idle circuits though.
    Blues4U likes this.
  10. DDDenny
    Joined: Feb 6, 2015
    Posts: 16,059

    from oregon

    Who are you and what did you do with Jim?
    swade41, scotty t, upspirate and 6 others like this.
  11. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 4,005

    from illinois

    I know folks do it all the time but , like it or not, the cylinders under the active carb run richer than the ones under the inactive one , IME it doesn't help the fuel mileage and hurts low end and around town or part throttle performance ..
  12. Come on Jim.

    Man,,,a new avatar pic and I don’t recognize you again.
    Man ,,,I think you, (were /are ) ,a spook for the CIA or something.
    Like a chameleon or something,,,,,Lol.

    Old wolf likes this.
  13. jimmy six
    Joined: Mar 21, 2006
    Posts: 11,017

    jimmy six

    My dual quad y-block is progressive. The stock ones were not. Mine is a recreation of the power package added at the dealer for law enforcement or bought over the counter for racing like NASCAR.
    If the engine is dead cold, at least a week of sitting, the only way it will start is fully depressing the gas pedal to squirt fuel into the front cylinder head ports. The rear carb has the choke which only closes enough to raise the idle to the first stop. When it's warm or just sitting for a day I don't need to touch anything. I do use the idle adjustments on the front the same as the rear setting with a Uni-syn. Only rechecked once in 4 years...

    Kahunakat..personally I think your nuts. It will get worse fuel mileage since the manifolds were not designed for this. I believe there was one completely open style that might have worked. But 245-270 SBC's idled on both and ran on the rear almost all the time. So did all the other brands... Good luck with ever you choose..
  14. big duece
    Joined: Jul 28, 2008
    Posts: 6,379

    big duece
    from kansas

    The Corvette 2x4 is designed to run off the rear carb, until you switch the pitch. I has runners that tie into the front ports. If you have a dead carb, make sure you leave some gas stains on it, otherwise it will stay clean compared to the one being used.
    Johnny Gee likes this.
  15. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,585

    Mike VV
    from SoCal

    Original poster...

    What the HELL are you thinking ?


    P.s. - Note to "big d"... Yea, for about the first 10 feet from a dead stop..! I know, my family had an original 56 dual quad Corvette.
    bchctybob and Desoto291Hemi like this.
  16. Ive seen dual quad intakes with adapters running two 2 bbl carbs. and let it idle and run on both carbs. seemed to work OK.
    Blues4U likes this.
  17. Torana68
    Joined: Jan 28, 2008
    Posts: 1,320

    from Australia

    Well that’s what I was thinking, make them work properly, I’d rather have a single 4 barrel and good HP than a dodgy dual quad with no HP.
  18. Possibly the OP has a FE that original cast intake weighd 80 pounds. a aluminum one weighs 30 pounds. and has a dual quad intake. find some way to make it work and save 50 pounds and a HERNIA.
  19. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,912

    dirty old man
    Member Emeritus

    I'm running my '31"A" with 355cid SBC on 2X4s with both carbs working full time as suggested to me by Carb King here on HAMB.
    The manifold is Edelbrock "Performer RPM AIR GAP" and carbs are Edel. 500 cfm AVS, stock jets and all I've done to them was check and make slight adjustment to float levels before installation. No bogs or flat spots, even when slowing down for traffic and then pulling away in 4th gear from 1200 rpm.
    Originally I was running progressive linkage, but decided I didn't like the thought of the front cylinders maybe rnning lean, plus wanting to maintain even fuel flow. I like it better hooked up straight, throttle response seems better, and it just has a better feel to it.
    However I suspect that without the AVS feature, you definitely would have to educate your throttle foot.
    Last edited: Dec 16, 2019
  20. oldsjoe
    Joined: May 2, 2011
    Posts: 2,569


    I've been running a dual quad intake, with twin Carter 500 Competition Series carbs for about 30 years, always with a progressive linkage. Drive the car approximately 3500 miles a year some more some less. But since the initial installation and tuning, have never had to touch them. Yes it idles a little rich in traffic, dyno says it's a little lean on the big end. The car runs down the highway just fine at 70 mph at about 2000 RPM. Why would you want to not operate on both? It really will not save you fuel, won't preform as it should. As has been stated the car will preform better with a single 4 bbl intake and carb than a dual carb set up with one inoperable. But you know what they say about opinions! Joe
  21. Put one carb on the intake and put the other carb in the trunk.
    bchctybob likes this.
  22. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,496

    el Scotto
    from Tracy, CA

    Don’t forget to get the fake magneto and fake oldsmobile valve covers while you’re at it! :D
  23. carbking
    Joined: Dec 20, 2008
    Posts: 3,292



    If a show car, run the linkage it came with. If a street car or race car, size the carbs to the engine, and run solid linkage.

    Old Wolf - I have an FE that came with a cast iron four barrel intake (and Holley). It now has an Offy dual quad (and two Carters with solid linkage). Both performance, and especially mileage are better with the two Carters than the single Holley. And you are definitely correct about the weight savings! The two Carters are as installed 21 years ago.

    egads and Old wolf like this.
  24. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 8,736

    Bandit Billy

    I like the idea of running only one carb and having the other there just for looks but only if you are mounting them on an empty blower case. I've witnessed actual bench racing stats that prove it is just as efficient as actual blowers and multiple carbs at car shows and parking lot events. Don't forget the blower straps and a gear drive set.

    Post pictures.
    Desoto291Hemi and dirty old man like this.
  25. DDDenny
    Joined: Feb 6, 2015
    Posts: 16,059

    from oregon

    jimmy six, Bandit Billy and Just Gary like this.
  26. chevy57dude
    Joined: Dec 10, 2007
    Posts: 6,921


  27. ball of socks in your pants will give you the look too.
    chevy57dude and swade41 like this.
  28. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,831

    Johnny Gee
    from Downey, Ca

    chevy57dude likes this.
  29. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,414


    Fake dual quads . As bad as some chic stuffing socks in her bra. Looks great until you try to get them perform.
    chevy57dude and 427 sleeper like this.
  30. liliysdad
    Joined: Apr 1, 2013
    Posts: 98

    from Oklahoma

    I have been told that if you will chrome the carbs, the two inactive ones will actually add five horsepower.

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