Mercury 1982 70hp Bluestripe Foot/Gear case

[FL-MNBoater]

I have a 1982 70 hp 3 cyl outboard. I own the Service Manual for the motor. The service manual also contains service information for the classic 50 hp four cylinder. In the manual, the foot for the 70 and 50 hp outboards, while they are interchangeable, are not the same. The 70 hp foot has a 1:68 to 1.0 gear ratio, and the 50 hp has a 2:1 gear ratio, making the 70 about 20% faster given the same RPM and prop pitch. In taking off the foot, and turning the drive shaft, I determined that my 70 has the 50 hp foot, with a 2:1 gear ratio. Is anyone out there familiar with these lower units? I would like to find the correct foot for my 70 hp outboard. I cannot find the part number for the 70 hp foot. Does anyone out there know the correct part number for the 70 hp foot? Thanks in advance.

 

[Chris1956]

Crowleymarine will have the parts list for your motor. You should be able to get the part number for the gearcase. Now, whether you can find a used gearcase for your motor is a different subject.

Alternatively, you could try a prop with 20% more pitch.