The Cessna 120-140 Association Forum

Hi everyone,

My engine RPMs will increase all on their own (e.g. while stationary at idle power) especially at low RPM. I have to have the friction lock tight to prevent this. This is something that recently started happening. I checked the linkage connection and it looks OK.

It's not a rapid surge, but does move if not locked tight.

Nick

Nick, if you are like me you have a self installed spring which takes your throttle to open should the linkage fail. A spring like that saved my bacon once in a different lifetime while flying over jungle in Africa. If there is a spring installed on your throttle it could be working against a worn friction lock.

Good point, John. I will take a look.

Thanks.

Nick

The throttle lever on the carburetor is pulled back at idle. The weight of the arm would like to be down or at about 3/4 throttle.
From John's experience, I can understand the thought of having a spring. Most don't have one. Your throttle cable is apparently very smooth.

Thanks for the input, Randy.