More.

The prop information was somewhat sketchy but latest appears first. From memory I think the last series of flights were on 22-8 and 22-10 Dynathrust props and I settled on 22-8 as best all around.

22-10 Dynathrust 6900-7000
22-10 APC 7300-7400
22-10 Dynathrust 6700
22-6 Dynathrust ???

The engine needs an air filter or velocity stack or air box. Shine the car headlights on a running engine at night and you can see a pulsating halo at the carb entrance. It looks like a donut shaped smoke ring. In the air stream a significant amount of fuel mixture would be lost. On whatever prop that was being used at the time an air door raised the RPM from 8600 to 8800.