4.1l 250cid needs to be replaced whats compatible

Me and my brother recently purchased a 72 boat with a MC. Now we find that the engine is blown, ie there is a nasty crack in the block. So Ive been searching like mad for a drop in replacement enging.

Currently it has a GM inline 6 cylinder, 4.1L 250ci cast iron block. What we are hoping for is dropping in a similiar 6 cylinder (or anything else) into the boat. Ideally we would like to hit the salvage yards and pull/rebuild a block from there(i can pull an engine for $200.00), the problem however is Ive spent a great deal of time looking for what is compatable, and keep hitting a wall.

So can someone tell me if there is a automotive replacement, and if not, what mod's etc will i need?

Thanks

EDIT: I believe it has a alpha II

Re: 4.1l 250cid needs to be replaced whats compatible

Ayuh,... You need a 250cid Chevy pickup motor of about the same Vintage...
The "Gotcha" is,... Many Don't have the Ear on the front starboard corner to mount the front motor mount...

Btw,... It Way Too Old to be an Alpha Gen.II... Try a Model 1....Pre-Alpha...

Re: 4.1l 250cid needs to be replaced whats compatible

So let me see if i have this correct, the only "Gotcha" is the motor mount? everything is is pretty swappable? ie manfolds etc

Re: 4.1l 250cid needs to be replaced whats compatible

ie manfolds etc

Click to expand...

No,... Just the bare "Long Block"....

Re: 4.1l 250cid needs to be replaced whats compatible

The auto engine really isnt built for the requirements of marine use.
The internal parts are what counts, cam, compression ratio. everything else is bolt on.Car motors dont operate at a constant 4400 rpm.low compression, emission cams, etc.Another option you have is to use inboard engine mounts that bolt to the side like a car ,but you will have to add the stringers for them.

Re: 4.1l 250cid needs to be replaced whats compatible

The first one I went to look at had the ear so I cannot really attest to the scarcity of the MerCruiser engine mount boss but I gotta believe somewhat rare.

Gotta have it no way around it. In this picture on the front left side of the engine on the edge of the timing cover is the Mercruiser engine mount boss, a ground wire was hooked up to the mount in its former Nova home.

I used my MerCruiser cam, lifters, and head and all the other marine specific bits.