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Original carb sizing?

Discussion in 'Small Block Tech' started by HwyStarJoe72, Oct 21, 2023.

  1. HwyStarJoe72

    HwyStarJoe72 Well-Known Member

    Hey all,

    Question... what would have been the original Q-jet CFM in '72 on an automatic Skylark 350?
    There's an old Edelbrock 1406 on the engine now (600cfm) and wondered if a 1906 (650cfm) would run any differently after tuning. Well, besides possibly eating more fuel.

    If the Q-jet was the usual 750cfm from the factory, would there be any change in performance changing to a 750cfm carb? I'm not concerned with fuel mileage.
    I'm putting a list of things to do when the car comes out of winter hibernation in 6 months. Maybe a TA intake, maybe headers...maybe.

    Thanks
     
  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    The original Quadrajet for a 1972 Skylark 350 would be 7042244. It would be a 750 CFM carburetor. That being said, the Quadrajet is a superior carburetor to any AFB clone provided it is correctly calibrated to the engine it is on. The air valve secondary design effectively sizes air delivery to engine demand. If you correctly calibrate an AFB, it will run well, as would any carburetor. Buicks ultimately like more air than they are supposed to. They make more HP with a larger carburetor. You might not notice it on the street, but you would see it at the track, on a timeslip, or on the Dyno.

    Get a correctly calibrated QJ for your engine. There are several guys here on V8 that can do that for you.
     
    Smartin and HwyStarJoe72 like this.
  3. Jim Nichols

    Jim Nichols Well-Known Member

    Newer Edelbrock AVS2 has the air valve too but not spread bore.

     
    HwyStarJoe72 likes this.
  4. alec296

    alec296 i need another buick

    Jetting an Eddie carb is a pain . I got a correct core carb and sent it to Quadrajet Power. Everyday Performance is good too. But I hear they are a bit backed up. Shoot them an email.
     
    HwyStarJoe72 likes this.
  5. HwyStarJoe72

    HwyStarJoe72 Well-Known Member

    I do have to admit I've had better performance with a Q-jet over a Holley in other cars . And tuning a Q isn't as bad as people think. I like the simplicity of an Edelbrock though. Jetting is no big deal.
    I've gotten all I can from this tiny 1406... but it's time to look for a Q-jet I guess. And it'll be the correct spread bore to match the intake. :)
    Thanks all
     
  6. Jim Nichols

    Jim Nichols Well-Known Member

    AVS2 has annular boosters too for good throttle response. Years ago there was a kit to fix Quadrajet leaks. I imagine the venders fix that too.
     
    HwyStarJoe72 and alec296 like this.

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