Evinrude 70 short shaft question

[arcticracer]

Today I scored the Evinrude 70 15" mid and lower unit I have been looking around for, complete with hydraulics! What I got was everything but the powerhead, electrical, carbs. etc. It is to be used for a high performance rig I will put together this winter.

The mid is a 1981 (E70ELCIM) but not sure about the lower unit I have. It has 4 splines on the shaft.

My question is, will later 3 cyl powerheads fit (splines) the older short shaft lower unit I have? I have a source for some late 80's vintage 56ci. powerheads.

Got it all for $100 (garage sale) including a new alum prop. Thanks in advance!

[Jeff Akers]

56ci wont fit, "differant spline" ! you have to go with the 49 ci block "or" You could put a 49ci crank in a 56ci block. It will work

[t2stroke]

The earlier crank will work fine in the 56 cu.in. motor. The first 56 cu.in. motors were 4 spline also. Be nice to use at least a forged unit(crank) as their hardness was deeper for the rod bearings. Of course it will take different rods, but rod bearings, wrist pin bearings and mains are the same.

Does your mid have 3/8" take down bolts? The earlier ones have 5/16" bolts, but you can drill out the mid. OMC had quite a few problems with the earlier 56 cu.in.powerheads. Try to find a 1994 or later (oval exhaust port), the earlier twin (bridge) ports need to be modified. It;s not difficult, but the later blocks flow water better. Be sure and get the thicker exhaust cover plate(#343864). It allows more water around the exhaust. Any block you use should have the overboard water (pisser) at the top of the block to get rid of trapped air bubbles. Be sure and use the 6 blade impeller.

BTY the model number you gave is for a 20" 1981 70. If you bought the mid dis-assembled make sure it is not a 50 H.P. They look similar and are much more plentiful, but will not work without an adaptor change. Amoug other things. FYI Dan

[arcticracer]

Hey Dan:

Oops, I have a 20" mid. I did not measure it before, the lower unit is 15" though. The mid has "3 cyl only" cast into it, it seems to be the proper 70 mid. It also has a single hydraulic cylinder.

Thanks for the tips, I am collecting parts for the project. Won't have to worry about any rules as it will be a toy. Now to find a 15" mid!

I'll send you a PM also Dan

Thanks!