Guys...
What prop would you put on an O.S. .46 AX running on a Goldberg Ex-Treme 330 s profile fun-fly plane for 3D type flight??

Thanks for any suggestions

APC 12.25x3.75 or 12x4. That engine loves bigger diameter props from a review I read a few months back. Just make sure it's broken in before loading the engine with the bigger props.

Thanks joe, I figured it would be something in that range

If those props turn too slow or spool up too slow, try an APC 11x5 or 11.5x4. Keep the diameter as big as possible while still getting a good transition on the engine. Someone recommended a Zinger 11x4 or 11x5 on another thread and that's a good choice too. The wood props are WAY lighter and spool up much quicker from my experience.

you might try an apc 12x4 and a zinger 12x4 - see which you like better

I really like the 12x4 APC on my .46 BB engines for 3D. It has thrust similar to the 12.25x3.75 with better throttle response.