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using a 2.5l 153 cylinder head on a 3.0l 181 engine

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winsok

New member
has anyone had any problems with this, i picked up what was supposably a bunch of gm 3.0l 181 engine parts, most of them are but we really wanted the Cylinder head cause mine has 2 cracks in it, well when i got my hands on the cylinder head the exhaust ports are smaller on the 2.5l head than the 3.0l and the manifold leaves gaps around the clyinder ports

maybe im missing something but any help or advice would be appreciated.

hopefully these pictures work.

on the top of the cylinder head the 2.5l says gm1 and the 3.0l cylinder head says gm2 not sure if that makes any difference new to the whole sterndrive engines

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Welcome aboard !

Let me ask you:

You have a 3.0 l block, you want to put a 2.5 l head on it ?

Yes or no ?

I just want to be clear so everyone who responds will respond knowing what you want to know.
 
Only thing in common with those 2 heads is they are both for 4 banger engines. I wouldn't even attempt to install the 153 head on the 181.

True, the 181 is basically a re-vamped 153, but there was LOTS of re-vamping, especially on the head, like port positions, runner sizes, valve sizes, combustion chamber size/shape and such. The manifold is entirely different too. That 181 is good little runner if it's right. I sort of miss the one I had. You will need to get a replacement head for the 181 to get her done right.
 
mani's the same.

I put my 2.5l mani on a 3.0 / 140 merc motor, omc mani.

The head now could be different if say the motor and mani are different series.

Year of head and year of motor?
 
chiefalen said:
mani's the same.

I put my 2.5l mani on a 3.0 / 140 merc motor, omc mani.

The head now could be different if say the motor and mani are different series.

Year of head and year of motor?
Click to expand...

Looking at his pic, the port configurations are entirely different between the 153 and 181 heads, as are the flange mating surfaces. Can not see how the manifold interchange could possibly seal up. Looks like the only thing the same would be the bolt holes.
 
sorry i kinda stopped watching the forums wasnt sure if i was ever gunna get a response, lol


but im still trying to find an afforadable cylinder head for my boat, i would hate to have to spend 500$ on it not trying to be cheap but with the baby on the way we need whatver money we got. So might have to be a project that will need to wait. lol

but im lookin to sell the one on the right, has some surface rust but its in good condition otherwise.

also there is a conversion kit were it converts newer high output small port exhaust on cylinder head to older larger port manifolds cause some of the newer heads have smaller ports like the one in the pictures above.
link here ----> http://www.michiganmotorz.com/mercr...-adapter-plate-high-output-engines-p-454.html
 
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also there is a conversion kit were it converts newer high output small port exhaust on cylinder head to older larger port manifolds cause some of the newer heads have smaller ports like the one in the pictures above.
link here ----> http://www.michiganmotorz.com/mercru...nes-p-454.html

I guess a lot of folks are putting the newer "High Output" engines with the smaller intake/exhaust ports in as replacements and need to use the older style manifiold on the installation (or buy a whole new setup). Not sure if the old / new heads are interchangable on the block. Should be, but combustion chamber size / configuration will surely be different.

Must be a pretty big demand if there is an "adapter kit" available. Just something about putting together a "Frankenstein" motor that makes the hairs on your neck stand up.....
 
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