Josh, as we discussed you are within the working range,changing the dia will make this worse you need more forward travel as we talked about/Darin

Josh,
you can try pm (private message) to mercruisermatt. he knows his kaamas and was helping me with my investigation of a 302 kaama formula that he did an engine rebuild on. he even talked about toe in/out of 1/4" with the tiebar making a difference in speed and knows what it should be set at. he has two or three sutphens at his shop with Kaamas right now. If you know what cam and headwork you have. he will probably know where your peak power is at. then help you and Darin determine the pitch change to get to that point.

Ram

first off you probably arent going to see 70mph. I had about the same HP in a 1988 311 with Kaamas and saw 67-68 mph

I believe I was running 14.5 x 32 4 blades

If I recall right you dont have to re-prop If you dont wish to. You can change the gear ratio in the drive itself for alot less $$$$
Gary @ Team Archer Marine was a big help with any ? that I had or getting parts

Good luck and nice boat you have there

Bob

by the way Josh, Team Archer is the evolution of the original KAAMA corporation. Some Original employees from Betty Cook's Kaama company , still repairing Kaama drives all day long.

OTIS311

Thanks for the input.
Your 311 was spinning some pretty big wheels. I really don't mind if I don't see 70, I just want to get as much as I can with the power I have (imagine that). I have talked to Gary from Archer last time I need help finding parts he was a big help. It's great to hear that other people have gone through these same problems, It takes alot of the guess work out of it. Might just have to look for some 600hp merlins!