will a 70 L unit fit 50

[RLT III]

I have a 3 cyl merc 50 there is a lower unit 89 70hp will it fit my 50 yr 81-83

 

[Texasmark]

Re: will a 70 L unit fit 50

No body answered but I'd bet it will. They came out with that 3 cyl pkg in midrange engines after retiring the 4 cyl's in that range, and with the hp being that close, it didn't make sense financially not to intermix parts to the point where they all may use the same parts other than decals, carbs, maybe intake reeds and linkages, and lower unit gearing.

Besides, my answer will bump this up where someone who knows for sure might spot it!

My 2c

Mark

 

[Texasmark]

Re: will a 70 L unit fit 50

My oldest sales brochure is '94. In that year they had a small 3 cyl 50 and 60 apparently off the same drawing and then they upped the gearcase (to 4 1/4" I believe) and used in on the larger displacement 84 vs 51 cu in displacement 75 and 90 and also on the new 4 cyl (loop charged) engines to 125 hp.

I'm trying to remember but when they first introduced that engine there were 3 engines in that category and they moved around in that range. Like one year it would be a 60 hp and the next a 65. I think when the 3 cyl loopers came out they dropped all cross flow 4 cyls but later reintroduced the 4 cyl at 40 hp. The 40 was in the '94 lineup. I just don't know if the 70 was part of that or not. I still think it was and at the time I was comparing it to the OMC 70 looper. I remember noticing that Merc used a smaller gear case in their new loop 3 cyl design run at a faster speed (lower gear ratio) than OMC's looped triple 70 turning a larger prop much slower.

Guess I'm not much help but I tried.

Mark

 

[Faztbullet]

Re: will a 70 L unit fit 50

Your post is kind of confusing as the 3 cylinder 50 was not offered till 1983/84. If it is the earlier 50 it is a 49 ci motor and lower unit will not fit as the 3 cylinder 70 (1987-2004) is a "big bore" 71.1 ci motor as crankshaft size and splines are different. A lower units below will fit your motor if you have the above engine:
1984-90 50/60hp
1973-76 65 hp
1977-83 70 hp

 

[RLT III]

Re: will a 70 L unit fit 50

well the plate #'s are 5797770 i was told it was a 50 and cowling is(red stripe&grey below) a 50 but the cover that snaps over the carbs says 70 thunderbolt ing(lighter blue) so heard it was 81-83 who knows i dont. I do know it's a 3cyl and will probably need a lower unit soon or get a new prop shaft cause it wobbles some and seems to be getting water in it and hopeing if i change it out every 3 trips it will last a year or two what do you think