Mercruiser 120 help Identify

[nearpar]

I was given and older fiberglass boat with a good running Mercruiser 120 engine. The boat is now gone and the owner did not know what year it was. I ran the motor on the driveway yesterday and noticed it had eletronic ignition and the smaller 5/8 size spark plugs.

1. can someone tell what year this motor is ( 4210595 )
2. Are there conversion kits available to go to eletronic ignition ? IS this one of them ?
3. Do the smaller 5/8 spark plugs work in the older heads ?

 

[Bondo]

Re: Mercruiser 120 help Identify

Ayuh,.... It's a 3.0l, not a 2.5l...

 

[achris]

Re: Mercruiser 120 help Identify

1. 1975
2. Electronic ignition is aftermarket. Original was with points. And that distributor you have, that's not standard issue either. Find a manufacturers name on it and someone will be able to help. (It does look like and early MSD unit, maybe)
3. 5/8" plugs were standard from about that year, but the older heads had 13/16" plugs, so will not work.

HTH,

Chris.....

 

[nearpar]

Re: Mercruiser 120 help Identify

Is the 3.01 a bolt in replacement for the 2.5 ?

Thank you

 

[achris]

Re: Mercruiser 120 help Identify

yes

 

[Bondo]

Re: Mercruiser 120 help Identify

Is the 3.01 a bolt in replacement for the 2.5 ?

Thank you

Ayuh,.... Externally, the only difference is the harmonic balancer,.... the 2.5l Don't have 1....