1988 american skier 351w

I am unaware of any tighter restraints of specs on marine engines when it comes to balancing. Production engines are balanced pretty well from the factory already and perform quite well all the way up to 4500 RPM. That's about as fast as you want to twist any marine engine (and that’s only occasional). Other factors start to become a concern above this, such as: shaft vibration and wear, packing gland wear, strut bearing wear and prop cavitation (not to mention fuel consumption). Most of the time, while pulling skiers, our tow boat motors stay at or below 3500 RPM. Racing engines are balanced to tighter specs because they constantly turn 9 plus thousand RPM. Since centrifugal forces increase exponentially with engine speed, any unbalancing quickly becomes a concern at that speed.

Imorrison, there are several things to consider when swapping in a replacement motor in your boat. First, is your motor "CW" or "CCW" rotation (as viewed from the from of the engine). All truck 351W motors are "CW" rotation. If your boat engine rotates "CCW" the camshaft and distributor will be different. Also the crankshaft will be machined differently and the rods and pistons may be different as well. An easy way to tell if your engine rotates "CW" is to look at the prop. If it is a left hand prop the engine turns "CW" and vice versa. That is unless your boat has a V-drive where the engine is mounted in the rear. Also I think most gear reduction units change the rotation of the shaft as well, so you'll need to see if you have one of those.

I have a book on small block Ford engines and it indicates there are no differences in the "truck" and "passenger car" blocks unlike the Chevy small blocks. However, the marine engines are equipped with heavy duty pistons, rings, bearing,.... and have a special "marine" ground camshaft even if it is a standard rotation motor. If your "truck" motor is from a pickup, it is basically the same as a passenger car engine and the only thing useful about it to your boat will be the bare block. Just some things to think about before you get started.

It is the front of the block. An oil galley is in the path of the crack. I have water in my oil. I am near Nashville. Thanks

I have a cracked block on a Ford 351W. I have been told that a 351W truck engine will be as balanced as the original boat motor. I was referred to this site for advice. I would appreciate any insite as to if I cough use this truck block & attach all the Indmar marine parts & the boat flywheel & make this work in my skiboat. Thanks for any input
Lanny