GM250 I6 w/ a cracked block

[white devil]

I have a 1975 Drummond with a GM250 I6, OMC 165 MC outdrive. The engine block is cracked. Can anyone tell me if there is a difference between the Marine GM 250 block and those used in cars/trucks? Thinking it will be cheaper to find one at a junk yard. Thought I read in a different forum that the main bearing journal sizes were larger in the marine blocks. Any advice is appreciated.

 

[windsors03cobra]

Re: GM250 I6 w/ a cracked block

I just did went thru this with this boat I acquired, I put out a ca=t call on craigslist for a Chevy 250 and got a hit the next day for $100.
Just got it running today, seems to run pretty good.
From a 74 Nova, I took all the automotive junk off except for the rotating assembly (crank,rods,slugs) and put on all my marine bits.

There is a very specific MerCruiser front motor mount on the starboard side, hanging off the side of the timing cover. You must have it.
In this picture the ground cable is attached to it, in front of the oil filter, you got a 50/50 chance on the blocks having the mount or not.

Good luck.

 

[Bondo]

Re: GM250 I6 w/ a cracked block

Any advice is appreciated.

Ayuh,.... This is the only "Gotcha" that I know of when swapping out the I6 Chevys....

There is a very specific MerCruiser front motor mount on the starboard side, hanging off the side of the timing cover. You must have it.
In this picture the ground cable is attached to it, in front of the oil filter, you got a 50/50 chance on the blocks having the mount or not.

 

[Alumarine]

Re: GM250 I6 w/ a cracked block

If the block you find is not from a truck, then you might need a marine cam.

The truck cam's are usually close enough.