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Technical Carburetor is making me nucking futs

Discussion in 'Traditional Hot Rods' started by Joe Warren, Apr 18, 2019.

  1. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    239 flathead. Offy wcfb square 4 pattern. Right now a list 1273 quad Holley that is way too big and operating very poorly. Car is around town car without any race applications. Mild cam.

    I want to use a 4-to-2 adapter and use a 2 barrel Rochester/Carter. If electric choke, has to fit between the tubes on the center-positioned heads. You people know everything: I was short-changed on carburetor knowledge, thinking God said, Schmarburetor, and took a pass.

    What to use?
     
  2. find a 49 to 51 Merc intake and swap it with the one you have. They will take a small base Rochester with no issues and probably cost as much as the 2 barrel adapter.
     
    Joe Warren and loudbang like this.
  3. deathrowdave
    Joined: May 27, 2014
    Posts: 2,116

    deathrowdave
    ALLIANCE MEMBER
    from NKy

    The Gods have spoken , the 2 barrel GM is your friend . A good one is one of the best bang for the buck on a flathead .
     
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  4. 302GMC
    Joined: Dec 15, 2005
    Posts: 6,024

    302GMC
    Member
    from Idaho

    If it's supposed to be a hot rod, put a good 4 barrel on it. I used '52-53 Olds & '52-'53 Cad Rochester 4GCs on the few flapheads I had with "equipment."
     
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  5. carbking
    Joined: Dec 20, 2008
    Posts: 2,716

    carbking
    Member

    The Holley list number 1074 was designed for use with a 1955 Ford 292. Has a Ford calibration, has spark valve for use with a FoMoCo distributor, and is one of the smallest 4-barrels made. Has the "square" (3 3/4 x 3 7/8) bolt pattern. Should be a good fit for a 239, especially if bored a bit, and a little better cam.

    Jon.
     
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  6. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    I like this one particularly because it agrees with what I was thinking, and even though I may not know of what I speak, I know to agree with my first thought. Actually, my first thought was to sell it. But she has become a part of our life.

    Are you thinking 2G Rochester?
     
  7. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    Yes.
     
  8. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    I'm staying away from Holley for a while. On the old 'Vette I ran a 650 a score of years back. It was a great Gush and Go (or Slobberator) but gas was a lot cheaper.
     
  9. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    I'll have to check it for dims. 59A's are tough to fit a carb between the pipes if it has any kind of choke operations.
     
  10. carbking
    Joined: Dec 20, 2008
    Posts: 2,716

    carbking
    Member

    Can't say as I blame you; however this carb is a lot smaller. CFM not published (at least as far as I am aware), but approximately 375.

    However, if you go to a non-Holley, you will probably need to also change the distributor, as the Ford distributors from that era generally require a spark valve on the carburetor.

    Jon.
     
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  11. Dave Downs
    Joined: Oct 25, 2005
    Posts: 862

    Dave Downs
    Member
    from S.E. Penna

    By
    Honest question here - what is a 'spark valve' on a carburetor?

    My best guess would be ported vacuum?
    Regional differences in definitions can be confusing.
     
    Last edited: Apr 19, 2019
  12. Truck64
    Joined: Oct 18, 2015
    Posts: 3,981

    Truck64
    Member
    from Ioway

    Ford experimented with a vacuum-only operated distributor (no mechanical ignition advance mechanism) that requires pairing with a proprietary type carburetor for proper signal. It utilized a specific vacuum source inside the carburetor Venturi or somesuch. I think that's what he's talking about anyway. Could be wrong.
     
  13. KenC
    Joined: Sep 14, 2006
    Posts: 385

    KenC
    Member

    The spark valve switches between manifold and venturi vacuum depending on load. It is external to on the carb and looks like a Holley power valve.
     
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  14. Dave Downs
    Joined: Oct 25, 2005
    Posts: 862

    Dave Downs
    Member
    from S.E. Penna

    Thanks for the explanation
     
  15. carbking
    Joined: Dec 20, 2008
    Posts: 2,716

    carbking
    Member

    Carter built a couple of WCFB carbs for Ford. The 2361s also has the spark valve, but was built for the 312 CID and is somewhat internally larger than the aforementioned Holley.

    Jon
     
  16. Joe Warren
    Joined: Aug 17, 2017
    Posts: 71

    Joe Warren

    Jon:

    I may have completely screwed up the system by using a Pertronix ignitor for use in my '42 59A, but it sure seems to start-run so much better since I changed it out (I had an extra dizzy that I used for the Pertronix and kept one intact with double points set correctly, just in case.) I guess what I'm saying is that the spark valve doesn't seem to be an issue. I checked at Mike's Carbs for a full explanation of what it does. Or, in this case, Did.

    I looked at a couple of WCFB with choke mounted high and inside, and something of that nature would work if I used an electric choke. I have a good Holley electric choke unit, but not sure if it will fit on the thermo choke housing.

    Still thinking a 2G, though, for simplicity and since around town, stow the 1273 if someone (in the distant future (fingers crossed)) wants to put it back to Rod status.

    Thanks for your insights, and to all who have replied.

    Joe
     
  17. jimmy six
    Joined: Mar 21, 2006
    Posts: 5,899

    jimmy six
    Member

    I have 2 WCFB's on my Y from 53 Old's.. Work great. When I ran a single 4barrel I used a WCFB from a 53 Cad. Rochester small base 4 barrels are good too.
     
  18. Just to ask the question, did you ever correctly tune the Holley 390? Or is it just "out of the box" and nothing done for your particular application? It is probably jetted too rich for your engine . . . just thinking out loud here.
     
  19. Garpo
    Joined: Jul 16, 2016
    Posts: 174

    Garpo

    Two issues here, carb set up and distributor advance curve, both need to work with the other. '49 8BA type distributor needs a specific vacuum source in the carb, other types with centrifugal are more forgiving..
    I went waaay out and found a wee four barrel on a Jap rotary wizz thing. It was a pig to set up. Much running up and down a quiet road with a gas analyser plugged in. Many times doing a plug 'chop' to check colour. Has been on the car since late seventy's and works well.
    My point is that any non standard installation is unlikely to be on the mark straight off. Tuning will need to be done, sometimes a lot of tuning.
    Remember a wise man once said "half of all carb problems are caused by ignition, and vise versa"
    Garpo
     
  20. Flat Roy
    Joined: Nov 23, 2007
    Posts: 391

    Flat Roy
    Member

    Joe
    I don't know about the sizes you mention, but in oval Street Stock racing everyone wants the 1-11/16" throttle bore versions. They had 1-1/4" and 1-3/8" venturi bores.

    If the track allows it, the 1-3/8" venturi version is supposed to flow about 500 cfm (about equal to the Holley 4412 two barrel which is also common for oval classes). Many tracks with limited rules don't allow Rochesters with venturis bigger than 1-1/4" which would flow slightly less, probably between 425 and 450 cfm.

    Keep in mind that 2 barrel carburetors are rated at a different vacuum than 4 barrels, so a 500 cfm rated 4 barrel actually outflows a 500 cfm rated 2 barrel. The 2 barrel would actually flow about 390 cfm when the difference in vacuum at flow testing is factored in.

    This is a quote from another HAMBER who knows his stuff
     
  21. Flat Roy
    Joined: Nov 23, 2007
    Posts: 391

    Flat Roy
    Member

    Joe
    I don't know about the sizes you mention, but in oval Street Stock racing everyone wants the 1-11/16" throttle bore versions. They had 1-1/4" and 1-3/8" venturi bores.

    If the track allows it, the 1-3/8" venturi version is supposed to flow about 500 cfm (about equal to the Holley 4412 two barrel which is also common for oval classes). Many tracks with limited rules don't allow Rochesters with venturis bigger than 1-1/4" which would flow slightly less, probably between 425 and 450 cfm.

    Keep in mind that 2 barrel carburetors are rated at a different vacuum than 4 barrels, so a 500 cfm rated 4 barrel actually outflows a 500 cfm rated 2 barrel. The 2 barrel would actually flow about 390 cfm when the difference in vacuum at flow testing is factored in.
    Quote from John 65h
     

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