Finding the right engine

[NickHansen]

Ok so just curious I have a 5.7L mercruiser and need a new engine. But Ive noticed that there are several different years like pre 1987, 1987- 1995, and 1996- present with subtle differences so besides the intake manifold bolt pattern and the valve covers and fuel pump can you just swap any out out with another? I guess what im asking is can i put a 1996- present in place of a older one? will the exhaust manifolds bolt up? will the motor mount locations be the same? will the rear bolt pattern for mounting to the outdrive be the same?

 

[Scott Danforth]

what do you have now? specifically year, and if you have it, the mercruiser serial number. additional information such as which intake - vortec (8 bolts on intake) or non-vortec (12 bolts on intake)

exhaust manifolds and bolt mount locations havent changed since the inception of the SBC in the 50's, same goes for the flywheel housing pattern.

if your swapping whole bob-tail, then it doesnt matter. if your swapping just the long block, then you need to worry about which year and flywheel size as the coupler depends on which crank and flywheel you have.

BTW, what is wrong with your current motor?

 

[NickHansen]

Well I had a local shop build a 383 for it. They put it in and did the initial break in. Put it in the water and ran it at 2000 rims and right away something was wrong. Pulled it out and took it back and it wiped the cam. So they "said" they tore it apart rebuilt it. Ran fine for about 15 hours but never pushed it hard. Then while cruising it started knocking so took it to a idle headed to the dock but the knock turned into a bang and the damn thing locked up. Won't know the true damage till I take it out. The shop won't return my calls of course. I have the worst feeling I'm going to pull it and flip it over to find out that it's really not a 383 but just a 350 with cheap Chinese parts. So anyway I can't wait to find out what's wrong with the motor and rebuild it. I'll will do that but just no time right now and I want my boat back. So the boat is a 1994 however the engine in it right now has 12 bolts in the intake and 4 in the valve covers which says it's pre 1987 right?

 

[NickHansen]

Oh as for a fly wheel I have no issues buying a new flywheel, coupler, and intake if it will work

 

[Bondo]

I guess what im asking is can i put a 1996- present in place of a older one?

Ayuh,..... That's very doable, you'll need an electric fuel pump, as there's no provision for the mechanical fuel pump,....