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Old 10-20-2009, 07:31 AM
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Ski Boat

Hey TRB, Nice ski boat. I'm a HotBoat guy too, 20ft Eliminator, hotrod sbc, mercruiser. I've always wanted to get my hands on a v-drive ski boat and modify it for high speed rather than its low speed pulling power. Alot can be done, gear ratio changes, prop size and pitch, engine hop ups, etc. But all these modifications are a trade off, reducing pulling power for higher top speed. In your case, you can have your cake and eat it too. There are several torque boosting modifications that will increase your top speed without losing low end grunt to get skiers up on the water.
About your engine, its likely 8.5:1 CR so it will run on any junk marina gas available. Most had 224/224@.050 .500/.500 lift cams. It likely has forged pistons. As far as reverse rotation thats a reverse ground camshaft & distributor gear. This is normally reserved for twin engine boats, I'm not so sure your engine is reverse rotation, got a feeling its just a reverse rotation propeller because of the v-drive gear box. The rectangle port heads are generally too large for operation in the 5000rpm range. The marine manufacturers had to use what GM had available in the Gen 4 era. There were the peanut port truck heads, the medium port pass car heads(781,049) and the big rect. port heads. When GM quit producing the medium port heads, marine manufacturers chose the still available rect. port heads vs. the peanut port heads that were weak on the upper end.
I think that stroking your engine is way overkill. You can probably get what you want with some torque boosting. Aftermarket high performance exhaust manifolds, change the rectangle port heads out to medium port with big valves, maybe a cam change, but in that order. Likely the exhaust manifolds will get you what you want.
You should get this book; Big Block Chevy Marine Performance by Dennis Moore. It is loaded with information specific to marine performance engines, tons of part numbers, specific camshaft recommendations, etc. Ok, there's food for thought, hope it helps. olnolan

EDIT- I had to leave the computer for a while, now I see it's a direct drive, not a v-drive. The torque boosting approach is still valid though.olnolan

Last edited by OLNOLAN; 10-20-2009 at 07:36 AM. Reason: a little late
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