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Thread: Primary bowl troubleshooting.

  1. #1

    Default Primary bowl troubleshooting.

    I have a 4160 on a '67 Mustang 289 installed in 2015 and it did sit a lot from time to time. Been after what seemed to be vapor lock issues. Replaced ALL fuel components and added Holley Mighty Mite pump at the tank, but still stalls if you drive too hard or uphill. Today when the bowl emptied after a medium drive, I decided to crack the float screw. Nothing came out. I cracked the rear float screw and sure enough it sprayed quite a bit. So I removed the whole float screw and valve. I gave it a crank and I could see gas slowly begin to circulate. I put it back together and cranked some more and eventually the bowl filled and I got it home. Before I rip into it, what could this be? Clogged inlet? Something stuck from the few years of sitting? I have a rebuild kit ready to go but I’d like to know what I should look for. Thanks for any input.

  2. #2
    Join Date
    Jan 2010
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    Brisbane, Australia
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    Default

    Sounds like the primary needle & seat is corroded and not dropping with the float. Pull the carb, strip it down, soak in carb cleaner, etc., then rebuild it. Gary
    Regards, Gary

  3. #3

    Default

    Will do. I'm not sure that's the exact issue though. I removed the needle & seat and looked down in the hole. From what it looked like to me there is a rectangular hole to the left at the very top where the fuel comes in. That inlet was barely flowing when I briefly tried to crank it. If you remove the fuel line there is a sintered brass filter inside. It seems to me that something in that area is restricting flow. I'm going to start tearing it down later today. My exact carb model: https://www.holley.com/products/fuel...arts/0-80458SA

  4. #4

    Default

    There's a filter just before the needle & seat. Unscrew the big nut that the line goes into and it’s behind there. It’s probably clogged.

  5. #5
    Join Date
    Jan 2010
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    Default

    OK, sounds like while you're sorting your fuel supply issue, you should look at filtering before the carburetor, and possibly fuel tank corrosion. Gary
    Regards, Gary

  6. #6

    Default

    There is a filter now, but the shop that did some body work let it sit for a long time and there was no filter then. I have to assume that caused the issues. Yesterday I took the primary bowl apart and soaked everything in carb cleaner, and rebuilt the seals. I focused on the sintered brass filter, though it didn't appear to be clogged. My float needle was a bit sticky, so I replaced it.

    I went for two test drives after and it fired right up each time. Took it up some steep hills and survived. For now it looks like the rebuild solved the problem.

    On a side note, the Holley rebuild kit that I purchased did not come with seals for the fuel inlet where the filter is. I had to reuse the old ones.

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