Mercruiser 140 181 3.0l Cylinder head question

[Winsok]

So i picked up a bunch of parts for my Mercruiser 140, Some alpha some pre alpha, all off a gm 3.0l 181. Should all the parts be interchangable?

my original cylinder head that i have i for the boat has 2 cracks in it, unrepairable.
So we picked up new heads from a guy off craigslist that had a bunch of parts i mean a whole lot of stuff. But the new cylinder head ports were the exhaust manifold lines up too are shaped differently, like instead of 8 individual holes its like there is 6 holes and 2 of them are shared ports.

Do i need some special gasket for this or what? or should i be find using a standard gasket as long as it seals all the way around the outside and what not? hope this isnt too stupid of a question. We have a new manifold that looks like it lines up with the new cylinder head ports being the same and what not, but will everything else attach onto the new manifold being that its from the same engine just different years.

 

[Bondo]

Re: Mercruiser 140 181 3.0l Cylinder head question

Ayuh,... Even if the head, 'n manifold don't match exactly,...

It'll run just fine...

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

But my major concern is the gasket, I've been reading about the manifold conversion plates that line up large port exhause manifolds to high output small intake port cylinder heads, on the 181 2.0l engines but I can't seem to find what any of these cylinder head ports look like.

When I brought the cylinder head in to get pressure tested and resurfaced the guy told me he doesn't want to do the work cause he don't think it will work.

 

[Bondo]

Re: Mercruiser 140 181 3.0l Cylinder head question

We have a new manifold that looks like it lines up with the new cylinder head ports being the same and what not, but will everything else attach onto the new manifold being that its from the same engine just different years.

Ayuh,... You've got 'em both in front of ya,...
Compare 'em to see if things'll bolt up...
Then use the gasket called for...

There ain't no book to explain mixin', 'n matchin'...
Ya just try it 1 way, 'n then another if necessary...

While not Perfect, I know the mismatched ports will run, just fine...

 

[Bt Doctur]

Re: Mercruiser 140 181 3.0l Cylinder head question

post a pic cuase that dosent sond right, this is listed for the 4 cylinders.

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

So I figured out by the casting number on the heads that's its a gm 152 2.5l cylinder head, the ports are a lot smaller. So what's my work around is didnt get them tested or resurfaced. Casting number 3905998 do I just use a gasket for that head going to my original manifold, and my regular head gasket should work right, everywhere I read that these 2.5l and 3.0l are interchangable.

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

So I put the 2.5l cylinder head up to the exhisting manifold and it doesn't cover the ports completly, on the top side, is there a work around for this or a way to make it work, I didn't have a gasket for the manifold will that cover the gaps?

 

[Bt Doctur]

Re: Mercruiser 140 181 3.0l Cylinder head question

That gasket fits 181 cu in, 120,140,2.5L, 3.0L that also fits the 3 manifolds for those motors.
Can you post a pic of your head and manifold?

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

Here is some attachments of pictures.. let me know if you need any thing else to help out
the picture is the head and the manifolds put together, with bolts in and everything but no gasket obviously, but its just the stock manifold off my 71 3.0l 181 mercruiser 140.

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

Just a bump cause I don't want this to get buried

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

Still lookin for help on this if anyone has any suggestions.


also the cylinder head on the top the 2.5l one says gm1 and the 3.0l says gm2 not sure if that has something to do with it. #

would one of those manifold adapter plates? like this?

 

[Winsok]

Re: Mercruiser 140 181 3.0l Cylinder head question

bump