replacing a 140 merc with a 170 merc

[RiggerMark]

Good day people,
Just got my next project, 1983 stingray cuddy, the 140 has been frozen and cracked, have a buddy that will sell me a good running 170, out of a 1985 fourwinds, so how much different are the mounts, the connection between motor and outdrive, and any other info that you would think help, thanks again for all the help, iboats rock.........Mark

 

[jim372]

Re: replacing a 140 merc with a 170 merc

that 170 may not have the same gear
research both engines and see what
gears are

 

[Scott Danforth]

Re: replacing a 140 merc with a 170 merc

so your taking a well supported motor out and replacing it with one that is difficult to get parts for?

 

[achris]

Re: replacing a 140 merc with a 170 merc

the 140 has a 1.98:1 drive and the 170 needs a 1.84:1... Not a big deal, just up the prop size... Will you be getting the exhaust pipe too? The 170 elbow will not line up with the 140 pipe....

BTW... You really don't want the 170... do a search on Mercruiser 470.... LOTS of problems...

 

[nola mike]

Re: replacing a 140 merc with a 170 merc

There are some problems with the 470, but if you're getting it cheap enough may be worth it. Probably will be a nice performance upgrade.

 

[RiggerMark]

Re: replacing a 140 merc with a 170 merc

thanks for sharing the knowledge, my last two tubs have been omc 4.3's, kinda new to the merc stuff, so are most of these engines gmc or ford products? and are the 120 140 and 170 series all 4cyl chevys, and would a 120 merc be under powering the boat? and one more, would the block of a 120 be the same as the 140, the 140 in the boat is badly cracked, i believe all else to be good, trying to use the search best as i can, us folks really are grateful for you more experience water folks, thanks all and good boating, Mark

 

[nola mike]

Re: replacing a 140 merc with a 170 merc

All the ” newer” merc engines are gm with the exception of the 3.7, which is a merc manufactured block with a ford head. Plenty of info on that engine with a search. Couldn't tell you about underpowered, since we know nothing about your boat...

 

[Bondo]

Re: replacing a 140 merc with a 170 merc

the 140 has a 1.98:1 drive and the 170 needs a 1.84:1... Not a big deal, just up the prop size... Will you be getting the exhaust pipe too? The 170 elbow will not line up with the 140 pipe....

BTW... You really don't want the 170... do a search on Mercruiser 470.... LOTS of problems...

Ayuh,.... The 470 is Unique, 'n is the Wrong direction to go....

 

[achris]

Re: replacing a 140 merc with a 170 merc

.. kinda new to the merc stuff, so are most of these engines gmc or ford products? and are the 120 140 and 170 series all 4cyl chevys, and ...

Merc used both Ford and GM until 1976, when they dropped the Ford engines. The GM engines used were the in-line 4 cylinder 2.5l and 3.0l and the in-line 6, 250 (4.1l). In 1976 Merc introduced the '470' series of engines. A 4 cylinder 170hp 3.7l Aluminum block, using Ford crankshaft, rods, pistons and one head from the 460 cu. in block. This engine was manufactured by Mercury themselves and featured some interesting 'innovations'. It was introduced to step into the line when the in-line 6 was discontinued, in 1981. The '470' (in many guises, including a 4 bbl 190hp unit) was used until 1989. It's 'replacement' was the GM V6, the 4.3l (262cu in), which was introduced in 1985 (although in 1983/4 Merc used the GM 3.8l, 229cu.in).

The currently available engine are all GM, the 3.0l (the 2.5l was dropped in 1989), the 4.3l (V6), the small block V8s (305, 350) and the big block V8s (496 and 502). The last year the 454 was used was around 2001.

HTH,

Chris......

 

[RiggerMark]

Re: replacing a 140 merc with a 170 merc

Thanks again, so the 120 is the 2.5 (til 89) the 140 is the 3.0, which seems to be a mainstay of 4cly. merc engines, and then the franken engine 170 which was the 3.7, agreed wrong way to go, seems like i should stick with the 140 (3.0l) and if so, what are the difference between the 120 and 140, same blocks?? diff strokes, cams, carbs............Mark

 

[RiggerMark]

Re: replacing a 140 merc with a 170 merc

and i think just one more question til i let this thread die, isthe difference between the merc 3.0 and the omc 3.0 pretty much all external stuff? probably the same with about all the engines (omc and merc) huh? thanks...............Mark

 

[Scott Danforth]

Re: replacing a 140 merc with a 170 merc

cam may be the same, however the block castings are different.