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Y-block carb CFM suggestions

Discussion in 'The Hokey Ass Message Board' started by north coast greaser, May 6, 2006.

  1. what is the best brand (holley, edelbrock, demon, carter...ect) of carb to run on a '61 292 y-block.

    and what is the best CFM that i should run on it. the motor is stock, other than headers.

    is 600cfm too much?

    what would the stock ford carb have for a cfm?

    thanks
    ncg
     
  2. Ford Freak
    Joined: Jan 5, 2005
    Posts: 826

    Ford Freak
    Member

    I have the original 312 in my 57 Fairlane. Still has the original Holly on it. I believe it is a 465 cfm. Runs great. Just for kicks I tried a 600 I had laying around - it didn't like it, guess it was too much for it, and ran awfull! A 500 would probably be ok.

    Bernie
     
  3. Paul2748
    Joined: Jan 8, 2003
    Posts: 2,201

    Paul2748
    Member

    The "experts" say not to go over 500 cfm.

     
  4. PWH42
    Joined: Jan 26, 2006
    Posts: 9

    PWH42
    Member

    The brand does'nt matter as much as the CFM.500 is the maximum to run on a stock 292.Any more than 500 is too much.
    Paul

    TANSTAFL
     

  5. thank you so much. i bought the truck with a 600 holley on it, and just couldnt seem to get it tuned right. i guess i will be getting a 500cfm.

    anyone have a spare 500cfm layin around?

    thanks again guys.
    ncg
     
  6. The Anarkist
    Joined: Jul 11, 2004
    Posts: 82

    The Anarkist
    Member
    from Canada

    Is the 600 vacuum secondarys or Double Pumper? A double pumper would definitely be WAAY too much carb!! maybe if it's vac. secondarys you could just jet it back?

    Even overcarbed it'll usually run Okay, just bogs. usually.

    Tailpipe black?
     
  7. wes
    Joined: Mar 23, 2002
    Posts: 717

    wes
    Member
    from san diego

    i just bought a 500 edelbock for mine, from talking to a few guys that run these, it may need to be down jetted a bit too.
     
  8. spoons
    Joined: Jan 1, 2004
    Posts: 1,738

    spoons
    Member
    from ohio

    FYI
    Check fuel pressure before you re-jet. Edelbrocks work best w/ 4.5-5.0 lbs. of pressure.

    Spoons
     
  9. t-town-track-t
    Joined: Jan 11, 2006
    Posts: 884

    t-town-track-t
    Member
    from Tulsa

    don't forget to take "cubic inches X redline / 3456 = CFM needed from carb"

    so in your case it might be (292 C.I. X 5500 RMP /3456 = 464.699)

    Adjust numbers to fit your application!
     
  10. ncg,
    Don't forget the Autolite 4100 4-barrel. The 1.08's are 480 CFM and came on a lot of Mustang 289's. The 1.12's are 500 CFM and came on a lot of 352's and 390's. I don't think I have any 500 CFM Holleys but I might have a 500 Performer. The Autolites are a little harder to find in good shape than a Holley but they are easy to work on and not bad with performance and fuel economy. The 2-barrel side of a 4-barrel is identical to a stock 2-barrel carb.
    If I remember correctly, the intake on the truck is a 56 or 55 Ford that takes a small base 4-barrel. It has an adapter to put a large base carb on it. You might have to put a fuel pressure regulator on it to slow down the electric fuel pump.
    Tom
     
  11. Another option is the Holley 390 cfm 4 barrel. It's always better to be too small than too large on a stock engine. The vacuum signal under the carb in the intake is what makes it work properly. If you have too large of butterfly opening, the vacuum drops to where the carb doesn't release enough fuel, hence the "bog". Small carbs have really crisp response.
     
  12. ok Hijack time....I am stumped on the math on this one....for this reason...I have a 1957 312 Merc Y-block.....same motor as the T-birds...I have seen them with dual quads(so 465 X 2)and they don't get over juiced......so how does one figure for that?......does that mean I can go with larger......???
     
  13. Dakota
    Joined: Jan 21, 2004
    Posts: 1,535

    Dakota
    Member
    from Beulah, ND

    This equasion is ok, but you have to factor in Efficency. motors are only like 60% efficient, so ou actually dont need that much carburation.
     
  14. i thought about the holley 390, but thought that since its smaller it would starve the motor.is that true?

    the factory carb would have been around 460cfm (?).


    anyone got a spare small carb laying around?
     

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