OK, I'm taking my trainer off the shelf and rebuilding it (as i've said before). I found 2 props with my plane and am not sure which one i should use. I have a K&B 40. Which would be the better prop, the 10-6 or the 8-4. Please help!!!

10x6 ...

10x6 is a perfect .40 prop. The 8x4 is for a .25 or a hot .15

Use the 10x6. The 8x4 is a bit small for that engine size.

Ken

Thanks, the 10-6 it is then!!