the difference between a OMC 2.5 and OMC 3.0

[myx17]

I have recently picked up a 1984 conroy X17 from my brother in-law. I need to do a tuneup on it, and I am having a hard time telling wich one I have. Can anyone help me out with the differences between the two so that I can finish restoring this thing. Thanks alot !!!

 

[myx17]

Re: the difference between a OMC 2.5 and OMC 3.0

I cant read the engine number, and the data plate is worn gone on the boat. I am just starting a rebuild of this boat and trying to figure what I have, sorry for the lack of info, I will take a photo tomorrow and put it up. Thanks for all the help guys. I do know the title states the HP is 120HP. Thanks again

 

[rodbolt]

Re: the difference between a OMC 2.5 and OMC 3.0

look at the front of the engine, if it has a rubber cam drive belt its a 2.3, if not its a 3.0.
there is a post about a motor exploding that shows pics of the front of a 2.3.
the 2.3 was made by ford and used in pinto,s and mustang II and a couple other small car applications over the years.
the 3.0 was never used in the US automotive market,was made by GM and was used in a lot of industrial and marine applications.

 

[cedarjunki]

Re: the difference between a OMC 2.5 and OMC 3.0

if your asking about 2.5 and 3.0 ......all external is the same...
the 3.0 has bigger pistons, bigger valves, and different cam.

 

[rodbolt]

Re: the difference between a OMC 2.5 and OMC 3.0

not enough coffee to properly see numbers .
anyway the quickest way to tell the GM 2.5 from the GM 3.0 is look at the balancer.
the 2.5 used a solid hub and the 3.0 used a conventional harmonic balancer with an outer ring bonded to the inner hub with rubber.

 

[a70eliminator]

Re: the difference between a OMC 2.5 and OMC 3.0

Ford 3.0 is a 6 cylinder, if that confuses things anymore.

 

[myx17]

Re: the difference between a OMC 2.5 and OMC 3.0

Rodbolt, thank you very much !! With your information and what I have already found I have determined it is the 2.5l. Ot turns out 120hp according to the title, and the crank harmonic balancer is a solid piece. Thanks all !!!