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quadrajet identification

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by lasvegas, Sep 9, 2001.

  1. lasvegas

    lasvegas 1/2 ton status

    Feb 27, 2001
    Likes Received:
    Las Vegas, Nevada
    In the process of installing my new ZZ4 motor. Never really looked under the hood of my truck as I was building it up so far but when I pulled the old engine, I noticed it had an edelbrok manifold and a quadrajet carb on it. The carb has a sticker on it that says "rebuilt by Holley" and I wondered if Holley ever sold rebuilt quadrajets? My real question is how do I identify which model I have, ie, the CFM of the carb to determine whether it is big enough for my new motor? Aren't there like two or three different sized quadrajets like a 600, a 750 and something else? The ZZ4 is about 355 horsepower. Does anyone know what CFM would be necessary for the engine. I would rather spend a little rebuilding this one than spend a lot buying a new one.
  2. Blazer79

    Blazer79 1/2 ton status

    Feb 17, 2000
    Likes Received:
    Guatemala, Central America
    I believe that Q-jets only came in 750 and 795 CFM, so it should be only one of these.

    With a quadrajet, it really doesn't matter the size and power of your engine, since the Q-jet is self-adjusting. The secondary top valves are vacuum operated. This means they will open to whatever your engine needs. My blazer came stock with a 795cfm Q-jet. I think the 750cfm models only came in the early 70's Blazers.

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  3. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
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    Roy WA
    Either 750 or 795 (800 as some call them) I've positively ID'd the 800 model as being stock on 83 and 84 K5's with 305's/700R4's. 750 will be plenty. Not sure why Gm went BIGGER in the 80's as emissions got tighter and tighter, but perhaps they could get a leaner mix (more air) through the 800's bigger primaries.

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