I think I read on this website a couple of weeks that the 470 to 140 conversion wasn't possible, as the transom unit was 470 specific. You would have to change all 3 major components to switch over to a 140, which is probably not economically possible.
Wonder why you see so many I/O's in boat salvage yards? Might have not been that way had Mercruiser designed the bellows units to be easier to work on. And, if the owners would make sure all the water was drained out of the engines.
So many great quality hulls are scrapped in boat salvage yards, like 22' SeaRays and WellCrafts. Re-engined with more modern engines, they'd be a dream boat at a reasonable price. Another option would to pull the I/O components, glass up the holes and put an aluminum external motor mount for a big modern 4 stroke outboard motor.
i dont know the answer to your question but one thing i have noticed here is you asked about a 140 going inplace of a 170 but yet everone is replying with information on a 470. Now i dont know a hole lot on the differant modle motors that was made so i could just be showing my ignorance here, or is there a type o some where?
Mercruiser had several names for the 470... 3.7L, 165, 170, 180, 190, 470, 485, 488... I didn't realize there were so many variations until I read a PDF the other day about it..
I would say it probably will. The big difference with the drive is the bolt pattern for the exhaust pipe is different. They make one for 4cyl and one for v6 and v8, not according to specific engines. So as long as the 140 is an alpha ready engine and the 170 is an alpha ready engine, the only thing that will be differant is the bolt pattern for the front mount. You will need to fill the holes for the old one and re drill for the new one.
My boat has a 4.3l on a drive for a 3.7l, the only problem I had was the y pipe the 4.3l needs has two bolts on top and two on bottom, the drive being for a 4cyl has one bolt on top, one on side and two one bottom, so only 3 bolts out of the 4 bolt holes line up, but it is more then strong enough to hold it. It was a risk I took to save 2k....and works perfect.
