I have a Cessna 150L with a newly overhauled O-200 engine. The engine has been flown twice. On the second flight I noticed that the RPM, during climb, was only 2300 RPM. The engine ground static run with the overhauled McCauley 69-48 (climb) prop is 2500 RPM. Right in the middle of the C150 TC specs. After the climb out, I level out to cruise configuration with the throttle wide open all this time. The engine will only turn 2500 max. NOW, the really strange part. With the throttle still wide open, I can dive the airplane until the RPM reaches 2700. I then level out to cruise configuration and the RPM now stays a 2700. If I climb the airplane again where the RPM drops to 2300 and then level out, the engine will again only reach 2500 RPM, max. All this with a continuous wide open throttle. If I dive again to bring the RPM back to 2700 and then go back level cruise, I now close the throttle to reduce to 2300 RPM and then advance the throttle back to wide open and the RPM will return to 2700. I did these scenarios several times. Each time the RPM would be limited after a climb, but not limited by throttle movement.

Never in my 50 yrs of working on these things, have I ever seen a problem like this. Nothing in the Harry Fenton files. It's not a tachometer problem because I can hear 200 RPM engine noise difference. I have one possible theory, but I don't want to influence the thought process.

Hey folks .......... any ideas ???????