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Thread: gas dumping out the front venturi

  1. #1
    Senior Member MASTER BUILDER
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    gas dumping out the front venturi

    at idle gas dumps out the front vetuuries. car still runs good at high rpms. i think it has to be the front power valve has a hole in it. if it was a sticking needle and seat(stuck open float) the gas would pour out the vents and not the venturis. am i correct. thanks art

  2. #2
    Senior Member DYNO OPERATOR
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    It'll come out of the boosters too, or anywhere else it can find a path. You may have the throttle blades open too far at idle, uncovering the t-slots. Try backing the idle screw off a bit and see if it stops.....

    Johnny

  3. #3
    Senior Member RACING JUNKIE curtisreed's Avatar
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    Re: gas dumping out the front venturi

    Quote Originally Posted by chevyart
    at idle gas dumps out the front vetuuries. car still runs good at high rpms. i think it has to be the front power valve has a hole in it. if it was a sticking needle and seat(stuck open float) the gas would pour out the vents and not the venturis. am i correct. thanks art
    No, gas will pour over in the booster if the needle is stuck or just set to high.

    Curtis

  4. #4
    Senior Member MASTER BUILDER
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    gas leaks

    hey juohn and door the blades are not open too much. idle has been that way for years and all of a sudden something started dumping the gas. took the needle and seats out and they seem fine. last thing is what i suspect(power valve.) the metering block is literly welded to the carb housing. only way i think ik will get it apart is to soak the whole body in gas till everything loosens up. anything better than gas to soaK THE CENTER SECTION IN. ANY SUGGESTIONS ARE APPRECIATED thanks ART

  5. #5
    Senior Member RACING JUNKIE curtisreed's Avatar
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    Make sure your float still floats also.

    Curtis

  6. #6
    Senior Member DYNO OPERATOR
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    gas dumpimg

    Spray the gasket with penetrating oil several times over a few hours.
    Last resort, with body seperated from throttle assembly, take a small scew driver at the bottom of the metering block where it won't be seen and pry it apart.

    Now about that power valve. If it is bad, the fuel will not be coming out of the venturies, I don't believe. It will be coming in below them.

    You can switch parts between the front and back bowls to find the problem also or just replace needle and seat and then float.

    To verify the float setting is not too high, turn the bowl upside down and the top of the float should not be below the top of the holes for the screws that hold the bowl on.

    Double check your fuel pressure. Reset it lower. 6-7# is normal.

  7. #7
    If the carb has been in service for a long while I would replace the needle seats anyway. They can look fine to the eye and not work so good anymore. This is of course if you dont have a float sinking on you.

  8. #8
    Senior Member RACING JUNKIE jmarksdragster's Avatar
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    Use a good carb cleaner or chlorinated brake cleaner, make sure you spray all air and emulsion bleed passages. Use a new power valve and fresh gaskets. Sounds like it just needs a good cleaning. Wear eye protection when spraying passages, stuff comes out from places you may not be ready for...
    Mark Whitener
    http://racingfuelsystems.myfunforum.org
    __________

    Good work isn't cheap, and cheap work can't be good.

  9. #9
    Senior Member RACING JUNKIE curtisreed's Avatar
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    Quote Originally Posted by jmarksdragster
    Wear eye protection when spraying passages, stuff comes out from places you may not be ready for...
    Good advice right there. Spoken from experience we have all had I'm sure. :lol: :lol:

    Curtis

  10. #10
    Senior Member MASTER BUILDER
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    leaky carb

    thanks guys for sall the input. basically what you are all saying is to rebuild the carb and i am going to do that. i will soak that thing till the metering blocks fall off on their own(i hope), and i will definitely check the floats to make sure they still float.. i did get squirted by the carb, taking it apart(one of the guys said to wear safety glasses when working on the old carb) and he was right. i got stupid and got wet. still waiting to get a look at old power valve. i really think that was the problem . art

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