I didn't really run my boat last year because of repairs and the first time out this year seemed to be running hot but stayed steady at around 180-190. I just pryed the 'stat out of my boat and it's a 180*! This is way too high isn't it? It's a merc 350 rebuit to a 383. What would you put in? I run only on fresh water.

My other concern is the RPM at WOT. I got her up to 64 speedo and was running 5500 rpms trimmed up a little. I'm turning a ss 21p 3 blade prop with an Alpha Gen 2 drive. Is this a little high? I am working on getting a 25p to try, good idea?

Thanks for all the help!

I would put a 140* T stat in it for sure. The rpm depends on where the engine makes its power. 5500rpms for a SBC is nothing. The Alpha won't like more tan that though. FYI, 2" in pitch = about 400rpms.