I am running 10% nitro PowerMaster fuel. I believe I used 10% when I used the engine in the 70's.
I think my engine is the baffle piston type, probably PDP. How can one tell by looking at the outside of the engine. I purchased the engine around 1971 I think.
The engine went to a very rich condition even when I removed the muffler pressure tube. I still think the problem is the muffler because the engine runs fine with the Dubro baffle plate muffler. I may try a running 5% nitro to see what happens.
Ralph White, Neoga, IL