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Thread: 4180C Help needed!

  1. #1

    Default 4180C Help needed!

    Hello. I acquired an '86 F250, 460 with a 4180C. There's fuel dumping out of the booster venturis at idle. Here's what I've done so far:
    Lowered both floats (no fuel running out level plugs), new power valve, closed butterflies almost completely, adjusted both idle mixture screws, blocked off EGR valve. Any thoughts?

  2. #2
    Join Date
    Nov 2014
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    Check the air bleeds on the top of the carb to make sure they are not plugged.

  3. #3

    Default

    Will do, thank you!

  4. #4

    Default

    I may have figured out what's going on. Apparently, the throttle plates are supposed to be completely closed, and the idle screws are supposed to set the idle speed as well as the mixture. Once the throttle plates begin to open, the "transfer slots" make the vacuum drop in the power valve chamber, which starts dumping fuel out the boosters. Those stupid idle screws are a pain to get to, but I think that with some adjusting, it just might work. Any thoughts anyone?

  5. #5
    Join Date
    Nov 2014
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    Ont. Canada
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    No, you're not correct. Get someone that knows a little about Holley carbs to set it up for you.

  6. #6

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    Thanks, 81, but I'll have to figure it out myself. I realize the plates have to be open a certain amount in order for enough air to enter. I could make it idle by hand-choking it, but even with the plates barely cracked, I could still see fuel dripping from the boosters. So maybe there's a vacuum leak. It'll be a week or so before I can mess with it again, so we'll see what happens. Thanks for your help! ��

  7. #7
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    If there's fuel dripping out the boosters at idle, the fuel level in the bowls is too high or there are air bleeds plugged.

  8. #8
    Join Date
    Jan 2010
    Location
    Brisbane, Australia
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    The siphon break bleeds in the metering block main well could be blocked.
    How many barrels are doing this at idle?
    Primary blades should be open about 1/2 after kissing the lever.
    Mixture screws about 1 1/2 out form seated.
    Adjust from there. Gary
    Regards, Gary

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