Much appreciate a recent discussion of head/piston clearances as it relates to performance and fuel. 

For my Brodak 40, which I and others note could use another 500 RPM, I'm considering running 25 or 30% nitro.  We'll see how that works out.

For my LA and SF 46 engines, 5% nitro is fine, though I ran too much oil one season, resulting in so much varnish the engine squeaked.  While the crock pot / antifreeze method recovered it, I will run 15% synth / 5% castor 2022.

Peter

Much appreciate a recent discussion of head/piston clearances as it relates to performance and fuel. 

For my Brodak 40, which I and others note could use another 500 RPM,

Peter

What plane and how heavy is it? The Brodak 40 is a very popular engine people use in the club I belong too. We use 10 nitro 22% oil fuel, APC prop 11.5x4. This set up will pull a 50oz Vector with ease using 59’ .015 lines doing 5.0 to 5.1 lap times, with a box stock engine. If you have one of the very first Brodak 40s, they had a liner timing issue and had less power than the newer version.
Al
Al

I think Al and Motorman are right.  The muffler exit was very small, and I recall drilling it out.  Maybe I have the one with the bad timing.

Peter