What is my CFM?

Discussion in 'The Venerable Q-Jet' started by jjones1983, May 2, 2010.

  1. jjones1983

    jjones1983 Well-Known Member

    What is the CFM of a 1972 Buick 350 Quadrajet? Is it 750? or 800? Will feed a basic stock 1972 455?

    Thanks
     
  2. flynbuick

    flynbuick Guest

    750 cfm which is th same as a 70 455. But you may want your carb or another set up for your engine.
     
  3. techg8

    techg8 The BS GS

    750 cfm.

    There are differences between the 350 and 455 carbs but the smaller carb can be made to work on a 455.

    The 350 carbs are SUPER lean. You can get close(r) with a 350 carb by jetting like a 455 carb.
    73 jets
    ~.043 rods
    CT 2nd rods

    The smaller carb may have nozzle drip issues on a 455 unless you add some idle bypass air. 350 carbs did not have it stock, and 455 carbs did.

    If you dont want to modify the 350 carb you should just get a 455 carb as it will have every thing you need done to it already.
     
  4. jjones1983

    jjones1983 Well-Known Member

    I'm swapping out my 72 350-4 for a 72- 455. I'm thinking that I can modify Idle Circut ( I have Cliffs book) and richen the up the Qjet. I would like to avoid purchasing a carb if I have one that will work. This is a street car, stock rebuild except cam and headers. Will only go to the strip to see how she will due, rest time cruising.

    Thank you for your input.

    John
     
  5. techg8

    techg8 The BS GS

    Lots of good info in that book.

    do all the recommended mods to your current carb, sized for your setup, and youll have a carb that will outperform any stock 350 or 455 carb.

    :TU:
     
  6. jjones1983

    jjones1983 Well-Known Member

    It is a great book.. He did a great job telling the story and making it understandable as to what is needed... Good job Cliff!
     
  7. Cliff R

    Cliff R Well-Known Member

    Thanks guys.

    As far as jetting to "richen them up", not required for all units. Many of the 244's use very small main airbleeds and much smaller main jets accordingly. I would NOT recomend to simply install larger jets without verifying the main airbleed "package" used with that particular carburetor.

    It really helps to free up the APT system in baseplate when working with the Buick carburetors, to provide full control of the part throttle A/F ratio from rich to lean.

    From what I've seen since visiting this Board, quite a few folks have went to HUGE main jets in the Buick carburetors to compensate for the lean part throttle condition with the stock primary metering rods sitting in .073" main jets. A smaller diameter metering rod or raising the power piston higher to a smaller section of the "B" series rods is the better course of action, IMHO......Cliff
     

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