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Holly carb jets

Discussion in 'The Hokey Ass Message Board' started by 61 chevy, May 7, 2012.

  1. 61 chevy
    Joined: Apr 11, 2007
    Posts: 891

    61 chevy

    Hey guys, I have a 283 stock engine with a holly 600 4 barrell on it and it is running extremely rich. I checked the main jets and they are .055 drill size hole. Do you think if I try a .050, it will lean up a bit? Choke seems to be Ok and the car runs good and does not miss, however it blackens the plugs. Any help will be appreciated.
    Last edited: May 7, 2012
  2. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,956

    gas pumper

    That's not a real big jet. You got other problems, I think.

    Maybe the powervalve is leaking. Dumping a little fuel all the time. It should seal up completely when not in use.

    Float level too high? Pump pressure over 6? Bad gasket where the body fits the metering plate.?
  3. BobF
    Joined: Dec 30, 2004
    Posts: 230

    from Poway, CA

    I agree with the other responders, check the power valve. I have a 283 in our 49 truck with a 1850 (600) and I don't recall exactly what size is in the primary side but 6X, probably 62 or 64. My plugs, due to our shitty CA gas look white, ever so slightly tan. I never had any 5X jets so I know they're not in there.
  4. gasserjohn
    Joined: Nov 9, 2008
    Posts: 1,219


    if you cannot correct with mentioned items
    check all flat surfaces by draw filing them flat

    besure to use quality gaskets.............

  5. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,562

    Johnny Gee
    from Downey, Ca

    You may have blocked air bleeds as shown below. #1 is idle curcuit and cruz #2 is high speed or main jet. If either get blocked, a richer condition will result. [​IMG]
  6. michev
    Joined: Aug 22, 2010
    Posts: 96


    The jet is not used for idle. I restrict the idle circuit to clean up a fat idle.
  7. Johnny Gee
    Joined: Dec 3, 2009
    Posts: 9,562

    Johnny Gee
    from Downey, Ca

    Just to clearify, this is done internally and not by restricting air bleeds. The OP may not know what your refering to.

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