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Engine Swap

I am new to boating but pretty up to speed on dry land engine stuff. I have fallen heir to a Mirrocruiser 25' (1980 Cruisers Inc) that I am going to have to rebuild. The hull is in really good shape and I can see a lot stuff has already been replaced - alternator, starter, prop. Everything else seems to work - the remote etc The Mercruiser lump has been lying uncovered for a few months and is partially siezed due to rainwater getting in thru the carb (I am soaking this thing neat WD40 in the hope I can slacken it off). The guy had left the flame arrestor/filter assembly off. If this "unsiezing" exercise is a failure, can I use use a Chevy 350 lump - the block and heads seem to be the same - just the oil pan is an obvious difference. Can I swap the bits over and make it a equal to a Marine version? The stern drive is a M/C - the one with the loop on the top (pre-Alpha One). The cooling system is closed system with a seawater pump driven by a belt on the front and has a hull intake just forward of the engine. Does this mean that I can ignore the sterndrive pump? Any help is greatly appreciated - I am not looking for a Rolls Royce rocket boat - I just want chug about the lake and go fishing!
Poolboy
Aug 2
2006
If the replacement lump is pre 1987 out of a truck The lumps should lump together pretty well. Be advised that non marine lumps might rust out if used in salt water. Jim

"Poolboy" <john@edronusa.com> wrote in message

Jim
Aug 2
Thanks Jim, This was a saltwater boat - now it will be a fresh water toy. Any advise about the stern drive water pump - should I just ignore it since it has a belt driven raw water unit drawing in from the botton of the boat? The thing came with a couple of deep cycle batteries - I thought a few heavy starts would wreck them - should I fit a high CCA 600+ regular sealed autobattery? Poolboy
Aug 2
Or just about any other small block. Pre 86 will be easier. The carb and alternator are about the only truly marine things about it. Even the oil pan doesn't really matter. That size boat you may have room for a big block as well. But you would need more brackets and things.

The fiberglass usually holds up pretty well on all boats. It's the encapsulated wood that causes trouble. Check the floor and transom carefully for signs of wood rot. Some people will actualy drill small test holes in places to see whatthey get out. If you do that just fill the hole back up with epoxy. If there is rot you might want to think carefully about putting any money in it.

The outdrive pump feeds in at a hose on the inside half of the transom bracket that it is mounted with. Some boats with alternate raw water pumps still used the outdrive pump for cooling the exhaust. If the pickup ports are open on the outdrive you might want to see if that hose is there or it looks like anything was hooked to it. You could always split the outdrive and see if the impeller is still in the pump. Also I'd be worried about the condition of the heat exchanger. If the closed system is shot you may want to convert to raw water cooling. Particularly if you're going to be in fresh water from now on. Also check the exhaust system. They corrode out as well.

"Poolboy" <john@edronusa.com> wrote in message

James
Aug 2
Belt driven water pump leads me to think you have fresh water cooling. If it Jim
Aug 2
   

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