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Thread: Nasty Rich At Idle

  1. #1
    BLOWN HOWARD
    What would cause this if my fuel pressure is good. Wich adjustment on Holley 750's can i make to lean out the idle circuit???

  2. #2
    TIMINATOR
    Is this a new installation? Did you change anything? or did this just happen all by itself? TIMINATOR

  3. #3
    BLOWN HOWARD
    Not a new application. Had the carbs re-done and told the guy it ran perfect and started up no problems. Just to clean up carbs and put all new gaskets. Ever since then it constantly fouls plugs on start up. and when i can get it running it is richer than hell. Once up and running its all fine. But when it sits for awhile and go to start up major pain in the ass usually resulting in fouled plugs.

  4. #4
    IMPATIENT 1
    Not a new application. Had the carbs re-done and told the guy it ran perfect and started up no problems. Just to clean up carbs and put all new gaskets. Ever since then it constantly fouls plugs on start up. and when i can get it running it is richer than hell. Once up and running its all fine. But when it sits for awhile and go to start up major pain in the ass usually resulting in fouled plugs.
    did you reset your idle mixture screws? run them all the way in and back them out a full turn, usually a good starting point from there with duals. i think i ended up at 1 1/2 turns on all 8 mixture screws on my 750's. starts within 4-5seconds and idles perfectly, surges but that's expected. my a/f ratio meter shows a good a/f ratio at idle too.

  5. #5
    DMOORE
    Have you checked the float level? If it's set too high, it could also cause hard starting and rich idle.
    Darrell.

  6. #6
    BLOWN HOWARD
    did you reset your idle mixture screws? run them all the way in and back them out a full turn, usually a good starting point from there with duals. i think i ended up at 1 1/2 turns on all 8 mixture screws on my 750's. starts within 4-5seconds and idles perfectly, surges but that's expected. my a/f ratio meter shows a good a/f ratio at idle too.
    Yeah i did the adjusting with the screws that was one of the first things i did. The floats are all good also.

  7. #7
    IMPATIENT 1
    Yeah i did the adjusting with the screws that was one of the first things i did. The floats are all good also.
    any chance it set long enough for a dirt dobber to clog up the bowl vent tubes? it'll pull a shiat load of fuel in if the tubes are clogged, i know from experience i ran my sj 1 day, parked it, went out the next day and it ran like shiat, damn mud dobber filled in 1 of my vent tubes

  8. #8
    502 JET
    If adjusting the idle mixture doesn't help, check your power valves they may be leaking. Check that the proper gaskets were used in reassembling the carbs. If still not better check for warpage of the metering blocks and main body of the carbs.

  9. #9
    BLOWN HOWARD
    May the Power Valves be bad and cause this from a back fire through the carb??? Because on one of the many attempts at getting it started it would back fire through the carb a bit.

  10. #10
    IMPATIENT 1
    May the Power Valves be bad and cause this from a back fire through the carb??? Because on one of the many attempts at getting it started it would back fire through the carb a bit.
    if they're the old style holleys without blow out protection, then yepper the valves are more than likely blown. if they are, buy a protection kit for them.

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