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Technical what carbs to use on gmc 302 when running 3 carbs

Discussion in 'Traditional Hot Rods' started by flying53gmc, Oct 7, 2013.

  1. flying53gmc
    Joined: Mar 2, 2005
    Posts: 357

    from M-boro, TN

    I am going to build my own intake for my gmc 302. It will be a mild build with headers, cam and maybe lighter pistons at some point, manual trans all in a model a coupe. I love the howard 5 carb intake that uses 97's but is this the best carb to run? I want the intake to have provisons for 5 carbs but run on only 3 with 2 as dummy carbs. I have a bunch of rochester B's laying around but not sure how they are performance wise. 97's are just so damn expensive for even a core carb so I'm not sure if I should run my rochesters of something else. Carbking will hopefully jump in here. I also have a couple of zenith one barrels which I think are great carbs. Please advise.
  2. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,956

    gas pumper

    I run 2 B's on my 235. When I tuned for draging it ran 17.3 and liked to have real rich main jets. now I have it a lot leaner and get 23 mpg highway.

    Driveability is great. very well behaved. smooth.

    If you like a pristine looking engine, the B's aren't for you. the gas that sloshes around over the top of them stains the carbs and intake. I believe the gas comes out from where the accelerator pump link goes in thru the cover. Maybe there's a fix for that?

    Three would probably be just right for a 302.
  3. flying53gmc
    Joined: Mar 2, 2005
    Posts: 357

    from M-boro, TN

    Thanks, gas pumper. the B's would certainly be my cheapest option. It might be hard for me to find enough of the zeniths to run. I have been impressed with them when I ran one.
  4. ol fueler
    Joined: Oct 6, 2005
    Posts: 935

    ol fueler

    See if you can find a couple or 3 BXOV2 Strombergs . They are single throat carbs but work very well. With single throats like the Bx has you could run 5 of them , we did on a 324 inch Fuel jimmie in a class C roadster , worked great. I think there are several articles on them here on the HAMB , do a search.

  5. carbking
    Joined: Dec 20, 2008
    Posts: 3,161



    Having said that, personally I would probably use Zenith (because GMC used Zenith originally), or Carters or Strombergs. As to exactly which Zenith (or Carter or Stromberg) that would take some research.

    As to the Rochesters? Give some thought to the following values for cores: Carter W-1 cores from $150~250., Stromberg cores $350.~$500., Zenith cores $350~$500., Rochester cores FREE with the purchase of any 3 rebuilding kits!

  6. $um Fun
    Joined: Dec 13, 2008
    Posts: 606

    $um Fun
    from Nor Cal

    I have some Stromberg EX23 single barrel cores and a few rebuilt ones that would work great on the GMC, the Studebaker Indy cars used three of these. PM me if you want them or more info.
    Joined: Nov 22, 2005
    Posts: 7,591

    from SIDNEY, NY

    Frank McGurk recommended the BXOV-2s for multiple applications, but be aware that there are several variations of them, and that they used the 216 size 2 11/16 bolt spread, which may or may not fit your intake. The specific carb number he used was 14-22, which would be stamped on the top of the carb top, usually on the passenger side. Other Stromberg single barrels (like the BXUV-3) used the larger 2 15/16 inch bolt spread like the 235/261 intakes had. The Strombergs are easier to tune for multicarb setups, due in part to the power enrichment setup. Rochester Bs use a vacuum piston that is more difficult to modify.
  8. bgaro
    Joined: Sep 3, 2010
    Posts: 1,189


    rochester 2g

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