Engine performance mystery

[Eric Brown]

Well Ron, you were close. When I wrote this thread, I had not performed any investigation as it was the end of the day. It appears that I cried "mystery of the month" too soon.
What I found today does not fully explain all of the events, but it was more than likely the problem. The RH exhaust tailpipe brace clamp had slipped down the tailpipe and dragged the brace rod with it. The throttle control runs under the brace rod. With the brace rod lowered, the the throttle control contacted the rod when the throttle was pushed open. This in turn would not allow the throttle to open fully. There was a 3/16" gap between the throttle arm and the full open stop on the carb with the throttle pushed full fwd.

I had to reshape the brace rod and reconfigure the rod attachment to the tailpipe clamp to make plenty of gap between the throttle control and the brace. I'll try to attach some photos. Should have taken the Harry Fenten advice that, low power issues are usually found in the engine control rigging. Will check out on next flight.