Need some help with my Q-Jet Carb

Discussion in 'The Venerable Q-Jet' started by mikeyfartsen, Jul 29, 2019.

  1. mikeyfartsen

    mikeyfartsen Well-Known Member

    My carb was rebuilt by a member. The problem I'm having is with the idle. I have a hand choke and make sure the butterfly is closed during start up. It starts right up. I need to keep the R's around 1100 for a few minutes to get it to idle. It idles around 7-900 RPM's. The RPM's wants to go up and down . It will stable out after a few more mins. When I drive it for a short time, it idles at 1100 and stays there. Can't kick it down. Vacuum seems good. I don't think I have a leak.
    The 462 is in a 1967 Special with MT SS headers 9.2:1 Keith Black Pistons

    I have a TM 290 H XLH 310 cam I believe. Not sure. Aggressive. I think some of the numbers are: Duration Int 280/290 Exh
    507 Int 538 Exh

    Carb: 75 Jets 45 Rods CK Secondary Rods Idle tubes .035 Idle Mix .092

    MSD box and Dist. 2500 Stall Auto Trans


    Last edited: Jul 29, 2019
  2. Rob Ross

    Rob Ross Well-Known Member

    You are in the ballpark. Have you confirmed that your idle mixture is set correctly? What is the rpm drop from park to drive?
  3. lemmy-67

    lemmy-67 Gold Level Contributor

    Check your linkage on the secondary flaps. Sometimes a groove gets worn into the rod, and the secondary throttle flaps stay open a touch. My Q-Jet developed this issue on a trip to Colorado a few years ago.
  4. mikeyfartsen

    mikeyfartsen Well-Known Member

    I will check the drop of RPM's. Not sure about the adjustments. My deceased friend spent sometime getting where it is now. Not sure of the sittings. Are those the ones you normally adjust 2 1/2 turns out? As you can tell, I'm not well educated in this area. A true novice.

    Len I will check. I would think when it was rebuilt, the person would have checked that issue.


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