OMC 140 swap for Merc 120

[LNM]

Hey all, I have a 1979 Beachcraft with a OMC 140 motor in it. I also have a Mercruiser 120 that is rebuilt. Can I swap the two motors out by changing the omc parts onto the merc block? The motors look the same except one is black and one is blue. The merc motor is from the 70's. I know where to look but the block id doesn't seem to be there.

thanks.

-Larry

 

[Howard Sterndrive]

Re: OMC 140 swap for Merc 120

should be a straightforward swap. externally, the 2 longblock motors should be identical. At the worst, you might have to swap oil pans and pumps, as there were 2 different sump/pickup arrangements

 

[LNM]

Re: OMC 140 swap for Merc 120

excellent! thank you very much for the reply. Is there any way to make up for the lost 20 hp? Or do you think i will even notice?

Any way you look at it though, the new motor should out perform the old tired one. (i think)
-Larry

 

[Howard Sterndrive]

Re: OMC 140 swap for Merc 120

that's a whole different issue
there's a noticeable power loss between a 140 and a 120, and there is no way to gain it back, but if the 140 is toast, you'll be gaining 120 horses, not losing 20.