Pretty new to stern drives.

[Stixx925]

I was just wondering what's difference between the merc 120, 140, and I think a 170 are all 3.0 i4cyl. I'm guessing the numbers rep HP. What's the major difference between? Can you swap say a reinell with a 140 to maybe a bayliner with a 120 or vice versa. What years parts are interchangeable? Main reason for asking is thinking of purchasing 2 boats 1 parts such as a reinell and a sea ray to restore. I don't own any boats yet this is just a theoretical question.

thanks

 

[Maclin]

The 120, 140 and 135 are same family of engine blocks but have some changes occasionally year to year, sorry I do not have details on those. The 170 is a 3.7l 4cyl, a completely different animal.

 

[Scott Danforth]

the 120 is a GM 2.5 liter, or 153 cubic inch motor that originally came in the Chevy 2

the 140 or 3.0 liter is a variation of the 153, with longer stroke and slightly larger bore. it never was an automotive motor, it was a GM industrial motor designed for gensets and pressed into marine use

both the 2.5 and 3.0 are/were used by Mercruiser/Volvo-Penta/OMc etc

the 470/170 is a Mercruiser only motor. it is the cast-iron head and 4 pistons from the ford FE family of motors, specifically the 460. it has a custom Mercruiser only crank in a custom mercruiser only aluminum block and uses a GM flywheel. because of the poor block design and the fact that the head is iron and the block aluminum, they are prone to spitting the head gasket if they overheat as much as 10 degrees. they also use the cam to drive the water pump, which would be ok, however the cam was never hardened and the seals wear grooves in the cam

I would suggest you stay away from the 470