Hi Randy
That is not typically caused by the engine, 99% of the time that is either from the fuel system or heat. First thing I would do is to change tanks, and check to make sure I had good airflow thru the cowling.
Also make sure the motor or any exhaust is touching the fuel system anywhere
Regards
Randy
Randy,
Thanks for answering so quickly. I have changed fuel tanks and pressure tested everything including filters and fuel lines. The airflow through the cowling is very open with no restrictions past the engine and at least three times as much area on the exit as on the entrance.
I really hadn't thought about the engine heating the fuel but it's possible. I'll check and see if I can insulate the tank from any wayward engine heat. Certainly, I'm flying in 100+ degree heat. Someone here suggested that 22% was too much oil and could be causing it but I've never had any problem with my other PA engines on 22% oil and 10% nitro.
Thanks for the suggestion, I'll let you know what I find.
Randy Cuberly