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Thread: Question about Holley 4150 mechanical secondary.

  1. #1
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    Default Question about Holley 4150 mechanical secondary.

    This SBC 383 ran fine for years until I took it out the other day and it had a miss and sounded lean on part throttle. It idles fine & revs fine, but when I give it gas in gear it just sounds like a big vibration. I'm guessing it's lean. At 30 MPH it just shutters down the road and sounds like a helicopter. Any experience with this?

  2. #2
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    Remove your air cleaner and gives all the air bleeds in the air horn a shot of carb cleaner. I've a had a blade of grass in a main jet also give similar symptoms. What model and list number do you have here? Gary
    Regards, Gary

  3. #3
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    It's a Holley 4150 mechanical secondary with the air horn machined off and no choke. Air bleeds are cleaned, but will clean again. Could it be the needle seats?

  4. #4
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    OK, next step is to pull the primary metering block, and make sure the IFRs (idle feed restrictions) are clear.
    Check the needle & seat functions correctly, sounds like it does, because it would either be flooding or the car would have power restricted. Gary
    Last edited by Gaz64; 02-10-2019 at 12:21 AM.
    Regards, Gary

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