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  1. #1

    Default 82 5.0 motorcraft 2brl carb running issues. Basic guides?

    First post!

    Going to start of with carb tuning issues. Right now I can barely get her to idle, but it's uneven, and when you tap the gas it'll hover before the rpms come back down. I've tried looking for float adjustment guides, and right now my idle screws are 1+1/2 turns out. My knowledge of Harley carbs is telling me I may have an intake leak, but I'm unsure.

    Anyone have any thoughts? Thanks

    Update: some closure on this topic, it turns out my electric choke was no longer receiving any power after doing some electrical work. The choke plate was stuck almost closed so it was running pretty rich. Since a lot of the old messed up wiring is getting replaced I did a manual choke conversion. I don't even need to use it down here in Florida. Thanks though guys.
    Last edited by 82Crustang; 08-25-2019 at 07:42 PM.

  2. #2


    I had a carb that did that, it was worn throttle shafts.
    Check with carb cleaner for leaks

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  3. #3


    Welcome to the site

    You can barely get it to idle, when (cold, warm, fully warmed up)? "Uneven" is a pretty good description of when I stop adjusting an idle mixture screw inward, and back it out 1/4 turn.

    There's a handful of possible physical reasons for a delayed return to idle... are we talking about a fully warmed up engine, with the choke fully off and the fast idle cam/screw nowhere near each other? Good throttle return springs on it? Nice easy moving throttle cable, and no binding at idle? Is there a solenoid/dashpot thing-a-ma-jig on there hanging up and/or delaying the return to slow idle?

    For Autolite/Motorcraft 2-barrels, 7/16" is a common dry (top surface of carburetor body, no gasket, to the toe of the float) float level setting. Unless way off, float level shouldn't be affecting idle.

    In general for the unevenness, try another 1/4 turn out to 1-3/4 of the mixture screws. A physical intake manifold vacuum leak won't be there and then not there. Fuel injection sorta thinking needs to be completely forgotten about when dealing with a carburetor, because computer-controlled fuel cobble-ization will fool you and add fuel to a vacuum leak. A constant present vacuum leak with an engine with a carburetor will not usually show itself as increased rpm, but with a roughness like running out of gas or stalling, from being lean, where previously adjusted idle mixture screws are/were adjusted correctly, where there's no vacuum leak.
    Last edited by Walking-Tall; 03-23-2019 at 09:22 AM.
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  4. #4
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    Oct 2014
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    The most common issue with those carbs causing idle problems is a leaking power valve. The diaphragm develops a leak and allows extra fuel to be drawn in at idle. Usually easily diagnosed by turning in the idle screws past where they should normally be. If the idle improves as the screws are closed (sometimes they can even be completely seated), then its likely the problem. You can pop the square cover off the power valve and if there is any trace of fuel under it, the valve is bad.

  5. #5


    These things are catastrophically simple, even compared to other carbs of the period (anybody remember the VV carbs from back in the day?) There are about six parts in a 2150 so, not much to go wrong. check for vac leaks first, then start the tuning and condition checks above.

  6. #6


    Thanks,I really didn't understand float level effecting my idle, coming from motorcycles, your float level either flooded or starved an engine.

    I have to do some more test running with the advice you've given me, I'll probably break the carb back appear and make sure everything functions smoothly as I'm really unfamiliar with this still.

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