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Thread: Street HP 750VS: What would cause the throttle shaft bores to leak fuel?

  1. #1
    Join Date
    May 2018
    Location
    Fair Hill, MD
    Posts
    72

    Default Street HP 750VS: What would cause the throttle shaft bores to leak fuel?

    Hello. The carb in question has already been replaced, but if this is the result of something I did, I'd like to avoid it with my new carb.
    The issue was fuel leaking out of the throttle shaft bore (mainly on the passenger side) and a noticeably loose fit of the throttle shaft in the bore itself (I could rattle it back and forth a hair). There was nothing putting and pressure on the throttle shaft and everything moved freely in the linkage. This carb had maybe 5000 miles on it tops, but it did spend a few months in storage off the car right before the problem began.

  2. #2
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
    Posts
    1,530

    Default

    Fuel only leaks out the throttle shafts, if the float levels are too high, and the engine boils the fuel out the boosters on shutdown. "I could rattle it back and forth a hair" is probably a good fit for a Holley, they need to have some movement, otherwise the shafts will bind when the throttle body is over-torqued, as many guys do. Gary
    Regards, Gary

  3. #3
    Join Date
    May 2018
    Location
    Fair Hill, MD
    Posts
    72

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    It would only happen with the engine running. I set the floats once and never had to touch them again. I did blow some dirt through the carb at one point, so is it reasonable that maybe the needle & seat were sticking, flooding the bowls, and causing this issue? The rattle in question would produce an audible click when I would move the shaft back & forth.
    Last edited by MrSinister55; 06-20-2019 at 07:13 AM.

  4. #4
    Join Date
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    Is this rattle in the shafts up & down, or side to side? Your float levels must be too high, you might need to replace the needle & seats AND the o-rings. Myself, I would rebush the throttle body with bronze bushing, and a vacuum secondary needs to be "loose" on the secondary, free movement versus snug on the primary. But to do this you MUST only have a single thin gasket or a gasket with limiting washers between the carb and the manifold. Gary
    Regards, Gary

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