Seek Q-jet tuning advice

Discussion in 'The Garage' started by Mastiff, Nov 15, 2003.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

    Jul 21, 2002
    Likes Received:
    Tucson, AZ
    This is my first winter since I rebuilt and installed a Q-jet on my 83 Blazer. The truck was off at the paint shop for 6 weeks, during which time it became winter. I could barely get the truck to run when I first got it out.

    The first problem was that I had the choke tuned too far closed. In the cold weather, the plate was tightly close and this was why it wouldn't run. I fixed this, so now it fires up well and runs on fast idle. What happens though, is that once I pop off the fast idle, it idles like crap until it warms up. It runs okay, but waiting at a light or something, it's on the edge of dying. I have the regular idle set to about 750 rpm in park, but it's down around 450-500 until it gets warmed up. This was not a problem in the warm weather.

    Any ideas what it might be? All I can think of is if the idle mixture was too lean or something like that? I thought I set it right, but it's so much harder to tune than the Edelbrock I had before (the recessed idle mixture screws are a pain to deal with).

    I'm not sure if it's related, but my PCV valve has started buzzing recently. This seems to clear up when it gets warm too. I thought it was an electric arcing sound at first, but it's the little PCV ball. The engine runs terrible if I pull the PCV valve out of the valve cover and put my thumb over the end. Is that right?

    Thanks for any help!
  2. Confedneck

    Confedneck 3/4 ton status

    Nov 1, 2002
    Likes Received:
    Lehigh Acres, Florida
    QJet Tuning on has a couple good links about tuning and setting up a Quadrajet.. /forums/images/graemlins/thumb.gif
    pop another 4 dollar pcv valve in it to see if it helps..

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