Quadrajets, found a few. Stickers

Discussion in 'The Venerable Q-Jet' started by carmantx, Sep 9, 2018.

  1. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Here is what im working with.
    Idle tube: .038
    Idle down channel: .065
    Upper idle air bleed: .065
    Lower " " " : .071
    Idle bypass air: .092
    Mixture screw holes: .084
    Main air bleed in main body: .058
    Comparing to the nums in ur book I look on the small side of all the holes. Turning the mixture screws in all the way did not stumble motor and barely lowed rpm. 3 turns to 7 turns out no differance. Only thing is it was smooth, and on the lean side. Rpm would increase with a touch of carb clean at the primaries.
     
    Last edited: Mar 29, 2019
  2. Cliff R

    Cliff R Well-Known Member

    Pretty "fat" idle calibration. Do you have some sort of "Pro-Stock" camshaft in your big Buick engine?

    I use the same carb with quite a bit less idle fuel and it easily feeds a 455 CID engine with a 289/308 @ .006", 236/245 @ .050" HR cam with .381" lobes and 1.65 rockers (.629") lift.

    What size is the MAB in the airhorn?.......Cliff
     
  3. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Sorry for the delay i got lost for a bit. .072 is the size of the MAB in air horn. Although I had overzealously removed the bump and venturi. So it must have had a weaker idel signal.
     
  4. Cliff R

    Cliff R Well-Known Member

    Why are you grinding away at the Venturi areas?

    I've set-up the smaller "750" cfm castings for Super Stock and FAST Class applications and some of them run into the 9's in the 1/4 mile over 135mph. To hack away at anything in the air path on a Q-jet for a street or street/strip application under about 750HP is a complete waste of time and may have less than positive results.

    The key to getting a Q-jet to work in a "high performance" application is to get the idle system up to par for your CID/compression ratio/cam choice, then get the car to hook, then figure out how to keep the Q-jet full so you don't get a bloody nose when it bounces off the steering wheel at the top of first gear when you suck the bowl dry and the car noses over really hard!......Cliff
     
    Brett Slater likes this.
  5. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    Haha. I think its because I found your book last. I found another main body of the same casting that I have not run yet. And I only removed the rib that connects the boosters to the wall. I learned from it and I will never remove a venturi again. It ran hard but without a dyno or quarter mile track who knows. I have no problems with getting it fuel. I learned a few things the hard way and had some interesting results and strange ones at times. But now Ive got one ready using your recipes, according to the very last one in your book, the eldlebrok carb. Except using the pontiac carb. Motor is still in limbo..
     
  6. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    What do you think was the cause for no change when adjusting the mixture screws.
     
  7. Cliff R

    Cliff R Well-Known Member

    Not sure, but that carb should delivery PLENTY of idle fuel for what you are doing.

    Does the engine speed up, smooth out and run better when you gently "tip-in" the choke flap or place our hand over the choke housing at idle to fatten it up some?...
     
  8. HotRodRivi

    HotRodRivi Tomahawks sighted overseas

    That engine is no more. RIP. If I placed my hand over the housing it would suck my hand and stumble. I wasnt savy with the tip in method at that time. But my method was to give a slight squirt of carb cleaner at the primary side and it would stumble slightly. butterfly was always held open by the choke pull off .
     

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