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  1. #26
    FEP Super Member gr79's Avatar
    Join Date
    Jun 2009
    SE Michigan


    Yup idle speed screw and set screw. You got the picture.
    Some way to see if engine responds to more fuel. Then its jet time.
    Forgot whether carb had holes or slots.
    Throttle plate below the hole but how much ??. Not much info on that out there.
    There has to be an equivalent way to mod the carb the same way without trial cutting.
    All i know is one carb i have does the same thing. The others did not. Bolt on and go.
    Playing with the engine vac lines and readjusting carb got things working until i found another carb.
    What and why is beyond me.

    According to my notes, did run dist adv from carb for a time. May have cured the bog. Slowed down advance.
    2005- jets 167, 219, 227. Turbo was not working, so leaned carb up a bit.
    2006 Had a problem with fuel drip into venturi, hard hot start. Reconnected charcoal can connection.
    Notes do not have which exact carb it was darn it. Ran at least 3 of them. Used have their issues.

    more reading
    Last edited by gr79; 03-21-2020 at 11:11 PM.

  2. #27


    Thanks, took the carb off and checked out the throttle plates. I loosened the primary plate screws and let the throttle closed, then re-tightened them. I could see a little daylight around it when closed, so I thought this might help. Then cleaned everything again and put it back on. It seemed to idle a bit better and I had to turn in the mixture screw a little bit. Lean spot was as before.

    Then I thought about the article about too much space before the transition holes see vacuum/throttle too far closed. In order to get the idle speed down I backed off timing quite a bit, and then used the idle speed screw to bring it back up. The lean spot improved somewhat! Then I switched the vacuum advance to ported vacuum and started over again. I now could get idle around 950-1000 rpm and 14-14.5 AFR. But, vacuum was between 15-16.5 and idle sounded a bit rougher. But the lean spot was damped dramatically! It will get to about 16.5-17.5 instead of sky high 19-20, and the bucking was much less. The idle mixture screw is out about 2.5 turns, and I think if I step up the idle jet I can turn the fuel back down at idle while allowing more fuel at cruise and just off idle.

  3. #28


    Had something weird happen today. I was fine tuning trying to get rid of the lean spot and put a larger idle jet in. It was too big and I had things too rich at cruise so I put the original one back in. Then when I started it up it ran really rough and I needed about four turns out on the mixture screw to keep it running. AFR was bouncing all over the place and the engine was bucking. Usually when I put my finger over the hole for the idle air bleed it will quickly die, but it actually seemed to smooth out a bit. It seems like it’s leaking air in the idle circuit and not pulling the fuel like it should. I tried putting the too big jet back on and it didn’t change anything. Thought maybe the air horn gasket, but it looks ok. Wtf could this be?

  4. #29


    Well, I figured that out and I feel like a moron. I spent probably four hours total disassembling, cleaning, reassembling, and fiddling. My wife was helping me out today and when it stalled once she said somethings on fire. It wasn’t smoke, but vapor coming out through a vacuum fitting that I must have bumped the cap off of when I was taking the air horn off yesterday. So now at least I’m back to where I started.

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