marine 350

I saw an add for a rebuilt 350 sbc. the add said it was a marine 350. whats the difference between a standard 350 that goes in a car, compared to a marine 350 for a boat.

 

I am no expert and can not prove anything, but I bought a so called marine sbc for a 51 gmc build. the engine builder said it has better rods (pink rods). I was building a blown engine and this was desirable for that.

 

The marine engine is more water proof and should also have spark arrestors on it. Sometimes they spin backwards and a lot of them (but not all) have a very narrow powerband.

The marine distributer may need to be recurved for street use, but it will be extremly water resistant as a rule. If it is reverse rotation you will need to change the camshaft and distributer. If it standard rotation and has a narrow powerband then a cam change and the recurve of the distributer will cure it.

 

The Mercruiser GM 350 in my 86 Mirage ran backwards and the cam was different. My brother hadn't pulled the drains before winter and it cracked the block. I put an automotive Goodwrench motor in it from the Chebby Dealer. Swapped the cam, dizzy, flame restictor carb/intake, boat manifolds etc and it ran fine. i would assume going back the other direction , you would swap an automotive cam into it, auto dizzy with auto firing order etc and be fine as long as all of the holes in the head and block are machined for you to hang p/steering , alternator etc.

 

Used it also depends on if the engine was cooled with a closed cooling system that was filled with fresh water and antifreeze or if the cooling system drew and expelled outside water to cool the engine. Engines that were/are salt water cooled often have a lot of corrosion in the cooling passages.

 

MR48,
Correct I hadn't thought of that. I don't live near the ocean anymore. When I did live near the ocean if or when we pulled the boat out of the water we always flushed them with fresh water. But I am aware that not everyone knows how to or is apt to properly care for a boat motor.

 

Everything mentioned above is correct. Is the engine you are looking at just a long block (heads and block assembly) or is it a complete, ready to run engine, with intake, carb, distributor, etc. ?

If you strip off all the parts that "marinize" a 350 engine you basically have just a car motor, but with a couple of possible differences. The engine should have brass freeze plugs (but I do that on my car motors too) and probably corrosion resistant head gaskets. The cam profile is usually more like a truck grind, made to top out at about 4600 rpms.

I have used engines that came out of boats for car projects (I was in the marine business so I had access to motors that I could score cheap) and when I rebuilt them I would change out the cam for something hotter and then use stuff like an aluminum intake, car water pump, flex plate, etc.

As was mentioned, internal corrosion is a huge deal and something you have to really look for. I have seen cylinder walls rusted so thin they actually broke through. Also be sure it is not a reverse rotation motor.

Don