Colin,

It doesn't take much air to make a big change. I have seen closer to 8000 on that prop and actually one of my engines will turn it close to 8100 when broken in. I've used loctite before, but didn't make much difference. I've just learned to fly it 20-30 flights, then pull it, and retighten everything and it stays tight forever after that. I don't know why this is, but it does. Also, if the engine is sucking a lot of air, it wont be able to unload in the air. I bet the flying RPM is several hundred higher than we are seeing on the ground. Hopefully tightening things up will make a big difference.

Arch