Rebuilt Marine Engines

Inboard marine engines are totally different animal than an automotive engine. For one the camshafts are different. Using an automotive cam has to have much overlap which can draw water back into the manifolds and hydro lock a engine. A marine camshaft is designed to be used under load at all times where an automotive camshaft is not. Also, knowing the right tolerances when building a marine engine is crucial, the tolerances of a street engine will not work in a marine engine, have you ever seen a fresh built marine engine lock up. The reason is the tolerances are wrong, and the reason is because that engine is under a constant load which generates much more heat where the pistons expand in the cylinder and scrub on the cylinder wall.

Another thing to consider is the cooling system in a boat open or closed system. Most boats running inboard marine is running a open cooling system, which means it is picking up water from the lake, river, or ocean feeding it directly into the risers to cool the engine. The advantage for this is constantly bringing in fresh water to cool the engine. The disadvantage is in salt water, it destroys the water jackets in the block and heads. Usually that means cylinder head or block replacement. The closed cooling system has its own radiator, holding tank and plumbing. The advantages with this you have control over the cooling system by using antifreeze to cool the engine. Also you can get multiple rebuilds out a close coolant marine engine.