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Thread: Carb Issues

  1. #1

    Default Carb Issues

    I have a 302 Ford that I had rebuilt with a small street cam many years ago. After break-in the car has rarely been ran as I've been working on the rest of the restoration. About two months ago, I rebuilt the carburetor, it's a 600 vacuum secondary Holley (was new when the engine was rebuilt). Drain the fuel from the tank and had the car running pretty smooth. I decided to take some of the bracket off and repaint the front of the engine and I did remove the distributor cap. I put it all back together and I'm having problems.

    Running rich, and the idle mixture screws do nothing.
    Low Vacuum at idle, around 5 inHg
    Pops through the carburetor when you accelerate it hard (on jack stands).
    I've had the engine stick at almost 3K RPM once and it stayed that way till I unplugged the vacuum advance from the ported connection on the Holley.

    I feel like I might have a couple different issues here. I've thought about trying to set the secondary butterflies and close the primary to see if that'll get the vacuum up and the take care of the rich idle. But why did this just start suddenly? What would cause the ported vacuum port to basically lock on? I opened the carburetor and cleaned it all out again and that made no changes.

    I'm a bit stumped, any suggestions would be greatly appreciated. Thank you.
    Last edited by psmith0803; 09-16-2020 at 10:28 AM.

  2. #2
    Join Date
    May 2018
    Monroe OH


    I'm going with a vacuum leak at one of the nipples under the front float bowl (those rubber caps can crack but look okay till you pop one off & inspect) or blown power valve.

  3. #3


    Can you see fuel dripping from the primary boosters at idle? That can be high float level, heavy float or leaking needle & seat.

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