Make SURE that the machine shop knows the differences between a boat and a car motor, especially a jet! In the Phx,AZ area, only a few do. We get to repair the carnage from the car shops all of the time. Weisco has instructions with the pistons that have recommended clearances. When in doubt, use the larger recommendation. A little extra piston/ wall won't affect anything but longetevity, and I can't even say when we had a jetboat motor in here that the bore was worn out, usually rust rings from the O.T headers, or from leaving the carb uncovered/rain. If the shop argues with you on the clearances (car guys think that the clearances need to be TIGHTER, because boats "have the whole lake to cool them") RUN!!!!! The block and heads do run cooler, but the pistons and valves run hotter because the boat engine is making more HP at the same speed as a car, and therefore they are larger and need that extra clearance. EVERYONE ELSE: DON'T USE HYPEREUCTETIC PISTONS IN JET BOATS!!!!!! There's a post explaining it. TIMINATOR
