Marine engine vs. Car engine?

[Doernuth]

So I need to replace a 1977 Merc 165. This is a GM 4.1L 250ci I6 engine. What is the difference between the marine and automotive version? I have a line on a used car engine that runs, can I use it or do I need to pay much more for a rebuilt marine engine?

 

[greg82255]

Re: Marine engine vs. Car engine?

Marine engines have different starters, alternators, distributors, carburetors, and it is dangerous to use any of those auto parts in a marine application. They can cause sparks and ignite any fumes in the bilge.

 

[Kainon]

Re: Marine engine vs. Car engine?

I actually have an engine from a '74 NOVA that the PO put in, the main difference in mine was the camshaft, the Marine has a little more lift & duration. also the mount on the front of the marine block for the RH side of the front mount, isnt there on the auto/truck block so my PO made a peice of alum, If you PM me, I might be able to get you a closer pic.

You'd need to use the electrical components as mentioned from your current engine, DO NOT USE THE HEI DIST !!! - its not safe.

You need to also pay attention to the year of the cylinder head and if it has Hardened Exhaust Valve seats, Pre-HEVS Heads needed LEADED Fuel to keep the Exhaust Valve Seats cool and from sinking into the head.

What's wrong with your current engine ?

 

[zbnutcase]

Re: Marine engine vs. Car engine?

If that car engine has more than 20k miles on it, it will need rebuilt before you can use it anyway, so you might as well rebuild yours

 

[jaxnjil]

Re: Marine engine vs. Car engine?

If that car engine has more than 20k miles on it, it will need rebuilt before you can use it anyway, so you might as well rebuild yours

i have ask..... you peaked my curiosity
why would a auto motor in good running order have to be over hauled before using in a boat????? regardless of milage

 

[Doernuth]

Re: Marine engine vs. Car engine?

Update, I bought a boat to get the engine. a 165 merc that runs well. Now I just have to transplant it to the boat....

 

[mcleaves]

Re: Marine engine vs. Car engine?

The difference is a lot more than the boltons (alt, starter etc) needing to be marine certified. You will need a different cam. If you get your hands on a truck engine you can start with that as a base. Also if it's not a closed cooling system (ie. it's a raw water cooled system) you will need to have brass freeze plugs, a marine water pump etc. Anything inside that engine that will touch water.

M