GM 250 cid

[CaptRon66]

I found an engine that might be rebuilt to replace what is currently in my boat. Mercruiser 165 .It came out of another boat,supposedly has a marine cam in it. Previous owner had some bolt on things way wrong. Automotive starter,alternator and electric fuel pump with no oil pressure shut off , hose spliced in the fuel line. The cylinder head is not the one Mercruiser used through the 70's It has much larger diameter plugs with metal gaskets. The casting number is 3895052. How can I find out if this head can be used ? Is there a GM cross ref for this? Also not sure how to check the cam...maybe I'll take that to a shop and let them tell me if it's marine. I applied 40 psi to each cyl at tdc. 4 exhaust valves leaking a lot. Air blowing right through.

 

[CaptRon66]

I meant to also ask....If the head can be used. Which plug and gap would be right?

 

[MikDee]

Re: GM 250 cid

Chances are it's a pre 70's head with the old style large 13/16" socket spark plugs. I don't remember the number they used, but you should be able to search it out. I'd guess all else is the same on the head.

 

[starsnstripers]

Re: GM 250 cid

Assuming it's an L6 I was told even if it were a truck eng. the cam differences are really not noticable like with other engines. Maybe use the head from your other engine? I'm doing an install now L6 165 mine is an auto but rebuilt it's missing the front right motor mounting (2bolt) tab on the block.I'm going to fabricate one for this season and install a 292 L6 i picked up next season. Good engines i hear. Good luck with it.

 

[Bondo]

Re: GM 250 cid

Ayuh,......

Don't worry about the Cam, unless it's Worn.......
And,....MikDee has the head Pegged,......
It's an Older head,+ I don't remember the right Sparkplug #s either.......

How can I find out if this head can be used ?

Drop it off at a Machine Shop for an Evaluation,+ Rebuild.........

 

[Old Tyme]

Hey Bondo

Hey Bondo

Ayuh,......

Don't worry about the Cam, unless it's Worn.......

Bondo, so you are supporting the comment by starsnstripers that there is not much difference between the truck cam and 165 marine cam?

I would be interested to know what other internal components are different between the truck L6 and 165 mercruiser engine.
This is what I had previously understood regarding the differences between the two:
1) Cam
2) Head Gasket material
3) Valve Seat material
4) Freeze Plug material
Is there anything else?

I ask because I have what I was told, is a 160 Mercruiser. But the engine was replaced and now I am not sure that it is a marine engine... The guy at the boat shop noted the orange block and wondered what it was. I am trying to figure out what I would need to do to convert to marine type.

Thanks- I value your opinion.