More Power for 75 Thompson Sterndrive

[CPlopper]

So, I have a real nice 1975 Thompson with a Mercruiser 120 straight 4, and I'd like to drop something bigger into the engine compartment. Any thoughts?

 

[chiefalen]

3.0 cevy motor easiest cheapest way to go find a 140 / 3.0 doesn't matter make, will fit right in and if you find a omc just change over the mani from the 120 with the carb and rise all one piece.

I went from a 120 omc to a 140 merc just changed over the mani, carb and rise to the merc.

You will get 20 hp more and it will make your baot feel like a different boat believe me.

No stringer work, no glass work it's just a straight change out.

Any 3.0 will work up to 87' after that you have problems with the flywheel and such.

Need to know how to pull the motor and do the work just ask.

 

[bondo]

So, I have a real nice 1975 Thompson with a Mercruiser 120 straight 4, and I'd like to drop something bigger into the engine compartment. Any thoughts?

Ayuh,... No Problem,...

You'll need to replace Everything from the pulleys to the prop, with the power of your choice....

Up grading to the 3.0l will gain only 20hp, 'n I doubt it'll even be Noticeable...