What's the difference between a "marine motor" and regular motor?

Question

I have a 1981 Beach Craft boat with an inboard motor and it is seized. It's a MerCruiser GM 350 rated at 260 hp. If I just bought a standard pre 1986, 350 engine could I just put it in? Is there anything special I would need to do to convert it over? Thanks for you're help.

Answer 1

You got some good answers, here's a bit more information:

1. different environment -- marine engines have to withstand a lot of shock & vibration, a lot of moisture.

2.  different mission -- a lot of sitting around idle then hard running.  No loafing along at 1200 RPM like an automotive engine -- it'd be like driving uphill 100% of the time, always in low gear, never coasting.

Answer 2

A block is a block,I have done what your are trying to do and yes it works,After you strip down the auto engine to the long block,Pull all the frezze plugs from the engine and replace them with copper ones every one dont forget one,Your marine oil pan will need to be used and the manifolds as well,If your carb was fine it will be marine grade it would be better to use that one not the auto style as well as the distributor,Over thirty years of boats i learned how not to listen to these shops and be raped alive.I figured it out and done it myself and your in the right direction

Answer 3

Half of the motor would have to be gutted, fitted with special pistons, different head, different cam shafts, timed different, and so on and put back together. The core block may be the same, but the engine is vastly different than automotive engines.

So in short, the answer is no.  Get with a reliable Merc service shop and explore what options you have available.