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  1. #16
    acceleration backfire GerryLP's Avatar
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    So do you mean back fire out the tail pipe, or backing out of the carburetor bore?

    GerryLP
    GerryLP

  2. #17
    Member 73shark's Avatar
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    He said (post #6) that it's the intake.
    Save the wave

  3. #18
    acceleration backfire GerryLP's Avatar
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    Quote Originally Posted by 73shark View Post
    He said (post #6) that it's the intake.
    Oh yeah, 73Shark, I am sorry about that. There it is in black and white. I actually missed post #5 asking the question.

    Backfiring through the carb is most likely a lean condition. Check the gasket at the base of carb, and if ok, then check for leaks by idling engine in park and spraying WD-40 to check for intake gasket leaks. If the engine RPM increases when you stream a shot of WD, then that would be a leaking area.

    Something is allowing air to change the fuel mixture downstream. This also explains the fact that it tends to do it at higher RPM's.

    Give it a try and see what you figure out. From the carb information, it sounds as if it has a big enough jet to maintain a good mixture at sea level, so that also makes the possibility of an air leak into the air /fuel mixture stream.

    Good Luck!

    P.s. Recall that the intake gaskets seal all the way around the ports, so the posibility of leaking in the underside edge of the intake is there as well. Sucking air from the underside should an increase in vacuum signal, but it will be fluctuating the gage needle wildly. (and moderately dampened gage less so than a undampened gage). The air is sucking would be oil gases from the lifter valley. The oil will end up coking the valves.
    GerryLP

  4. #19
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    it turned out to be the carb.
    i put a buddies on to try and backfiring went away.
    i dont know what was up with it. i went through maybe a can of wd40 trying to find a leak and couldnt.

    vacuum gauge was holding steady so i know it couldnt have been a huge leak if it was the carb gasket.

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