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Thread: Minimum Idle RPM

  1. #1

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    Minimum Idle RPM

    I notice my idle RPM is a little high-- slightly over 800-- after replacing the carb. My mechanic is doing some final tweaks and was going to adjust that. I believe somewhere around 650 is about the minimum but wanted to confirm that that is what I should see.

  2. #2
    SJ's Avatar
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    Dan, We use 600-650 on wheels. I used to set mine as low as possible 450 - 500 when on floats to minimize idle thrust. 800 will almost keep a light super cub in the air!

    sj
    "Often Mistaken, but Never in Doubt"
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    Yeah-- that is sort of what is happening to me! I settle down into ground effect and float for about 300 feet.

    On the ground, I am having to ride the brakes while taxiing.

  4. #4
    cubdriver2's Avatar
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    My stroker in my J4 will idle slow enough that the impulse will clatter. Idle below 500 rpm make a huge difference in landing distance. My yellow cub with the composite prop won't idle as low

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  5. #5
    n40ff's Avatar
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    Engine quits on final, it"s too low.
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  6. #6
    cubdriver2's Avatar
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    Quote Originally Posted by n40ff View Post
    Engine quits on final, it"s too low.
    If it's too low it won't quit on final, it will quit as you touch down. But we all fly a safe height to touch down, right ;- )

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"
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  7. #7
    RaisedByWolves's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    If it's too low it won't quit on final, it will quit as you touch down. But we all fly a safe height to touch down, right ;- )

    Glenn
    Dead stick funeral fly by?


    Sent from my iPhone using Tapatalk

  8. #8
    n40ff's Avatar
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    Quote Originally Posted by cubdriver2 View Post
    If it's too low it won't quit on final, it will quit as you touch down. But we all fly a safe height to touch down, right ;- )

    Glenn

    Well, "as you touch down" is still "short" final I guess......... Not much of a problem with a SC or even a J3 but a real PIA in the J5A to be stuck in the middle of the runway w/o starter.....with a &^%^# Lear Jet benind you. BT/DT

  9. #9
    cubdriver2's Avatar
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    Quote Originally Posted by n40ff View Post
    Well, "as you touch down" is still "short" final I guess......... Not much of a problem with a SC or even a J3 but a real PIA in the J5A to be stuck in the middle of the runway w/o starter.....with a &^%^# Lear Jet benind you. BT/DT
    Mine doesn't quit

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  10. #10
    55-PA18A's Avatar
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    Mine is set about 500. I sometimes get that mag rattle. What is that, and does it cause any problems?

    Jim

  11. #11
    cubdriver2's Avatar
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    Quote Originally Posted by 55-PA18A View Post
    Mine is set about 500. I sometimes get that mag rattle. What is that, and does it cause any problems?

    Jim
    Joe, the Slick guru at Kosh says no

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  12. #12
    Steve Pierce's Avatar
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    Mine has a pretty good lope at idle.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  13. #13
    DJ's Avatar
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    I turned mine up to 600-650. It had an unnerving tendency to quit when I closed the throttle on an mild uphill landing if I had the mixture a little lean.

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