I know its not 1/2 A but its on the small side nonetheless. I was just given a 1/2 A Pathfinder with a new .074 bolted on the nose. I just started it this evening after doing some preliminary polishing and cleaning of the inside. The engine had a Zinger 7x4 on it. Once running I wanted to bring the rpm's up fairly high . It sounded a bit anemic but tight as well. I gave it a minute or so and then the needle started to work a touch better. The rpm's were coming up but I then shut it off to cool. I was wondering if the 7x4 is a bit to large. I currently use that size prop on my Norvel .15. I was figuring a 6x4 might be better especially at first. I don't know anything about this engine other than its identical to my smaller Big Mig counterparts. I don't think the 6x4 would hurt as I've found these engines to be pretty much bullet proof. I'll take any advice as I don't own the instructions on this one. Thanks, Ken

I know the .049's loved a 5X3 so I'd say a 6X3 would be plenty.  They like to rev.

Hmm. I have no experience w/the .074 "yet!", but my .061's will turn a 6x2 25000 rpm in the air.
I would experiment with something larger/low pitch for the .074.
(and please let us know how it works out!) ;-)
Roger V.