The stamps on my props are a bit difficult to read, but the one on the motor appears to be a 9 1/4 X 9 pitch. The other, which I haven't tried yet, appears to be a 9 1/4 X 11. While looking at prop selectors, most props for this engine are listed as 9 7/8" diameter, so either mine are just old or I can't clearly make out the stamps. At 6K elevation, I doubt I'll see any improvement with the 11 pitch but I may give it a shot in the future. I have a tach connected to the motor, and while I don't think it's terribly accurate, it will run close to 6K RPM at WOT.
Last edited by SockPuppet; 07/18/19.