Jetboat engines are 330HP, most truck engines are in the 245HP range, The cam is much smaller, the valves aren't nearly as good quality, the guide and piston/wall clearances, along with every other clearance in the motor is too tight for marine use. BUT, if it has some miles on it, it may last for a while. If you get greedy and change the cam and intake manifold when you discover that an 18 foot boat usually runs about 45-48 MPH with a stock truck motor, you will break it. Pistons, bearings, and valves in that order will fail. The cash saved by buying something wrong for the purpose and being dissatisfied with the performance is usually waaay offset by the credit card costs to do it right the first time. If you are kidding yourself and know that you probably never will have a good motor, go ahead and use the truck motor, keep in mind that when it fails, you're probably gonna be looking for an undamaged block and at least one head, and usually a crank too. Then again, whats your installation time worth? Oil, filter and other little stuff? Whats the worry about being stranded out in the middle of the lake worth? Make your decision and live with it. I have about a dozen+ engines come in here per year that were just stuck in boats, the cast pistons explode into gravel in the pan, the rod goes through the block, and the head on that side is junk, got one in here right mow. Moral of the story: if you do this, leave the motor completely stock, keep the timing conservative, and keep the full throttle time to a minimum. P.S. look-up the old HOTBOAT article:"A CAR ENGINE IN A BOAT?" Good luck, you'll need it. TIMINATOR
