Consistent miss when adjusting throttle or mixure

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    • July 2, 2020 at 09:22 #14297
      Bob Schwindt
      Participant

      Flying out of a sea level field in my 78 Cheetah, I consistently get a small miss after leveling off. It happens when I throttle back to cruise setting or lean the mixture. It is so brief but there. During flight I can adjust throttle or mixture and it does not happen. The carb was rebuilt last year with 100 hours on it. Began noticing maybe 25 hours now. Engine is strong and smooth. Compression in the 70s. Roughly 200 hours on rebuild. Any thoughts or recommendations would be appreciated.

    • July 2, 2020 at 11:06 #14298
      Roscoe Rosché
      Keymaster

      Sounds like you had the ‘Grumman Bump’ You will need to have the pepperbox nozzle installed in your carb.

      FYI

    • July 2, 2020 at 11:57 #14299
      Bob Schwindt
      Participant

      Roscoe
      Thank you for that direction. Was not familiar with that term so I did some research. Interesting and the info I read is exactly what is going on. A bump with power changes or mixture. I will plan to make that change which hopefully will solve the bump. In the mean time, with that being the issue, is it more of a nuisance and safe to fly?
      Thank you
      Bob 251RX

    • July 2, 2020 at 13:53 #14303
      Roscoe Rosché
      Keymaster

      Bob,

      Mine did it with the first power change after takeoff, so it was a nuisance. Flew with that for 2000 hours in my AA5 until I overhauled the engine to 160 and had to have the carb redone as well.

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