ALTERNATE LOWER UNIT

[crankshaft]

This 1982 70 hp Mercury lower unit I have will fit other Merc engines. I think as low as 35. Nit sure on the upper side like 80 or more. Anyone know?

 

[leachy]

I think if you look at the parts diagram it will tell you.

 

[racerone]

Correct it will ---" fit " ----down to a 35 HP---------Will not fit 80 HP.------And the 35 / 50 HP version had a different gear ratio then the 70 HP version. I believe.

 

[crankshaft]

I guess that might mean I would have to find a 70 hp?

 

[racerone]

Thot motor is not considered one of the factories best efforts..-----I would not want one on my boat.

 

[crankshaft]

Reasons ?

 

[racerone]

Many suffered from issues with top cylinder dome cracking.----And lower units are not hefty.----Yes it is a light weight motor.

 

[crankshaft]

I will look at the top cylinder with an endoscope. It is also displacement at only 49 ci. that went up in 1984 to a big increase. Have a light ply and epoxy cruiser that I am restoring with a light transom that would work great with this outboard.

 

[racerone]

Was the 84 model the same type of 3 cylinder with internal reed valves and 2 carburetors ?---Or a totally different engine ?

 

[crankshaft]

Internal reeds I believe, manual tilt. Not sure, but they did a lot of changing things in those years. Cylinders are good and fairly high compression 130 ish. That choke/enrichment valve, depending on who is doing the writing of the manual it seems, seems kind of jury rigged, maybe one reason the outboard has a bad rep?