Advice on 1988 70hp rebuild.

[bonz_d]

Some might remember that The Alumacraft I bought last fall had a blown 1988 Evinrude 70hp on it and after disassembly I found that the splines in the crank are wiped out otherwise the engine is in pretty good shape.

Well I've been contemplating rebuilding this over the winter after not getting much interest in selling it out as a parts engine. After looking through BRP's website I was able to determine that the cranks and piston assemblies from the 60hp, 70hp and 75hp all have the same part number all the way back to 1983. Though I also see that there are a multiple of numbers for the crankcases throughout these years. Anyone have any clue as to the difference in these crankcases? I have also noted a few changes with cylinder heads.

Anyways the thinking is that there are always engines available on CL with a blown cylinder and I should be able to aquire one reasonably cheap to salvage a crank from.

So is it worth the time and effort? Right now I have a line on a 1983 75hp that is very clean and runs but has low compression on one cylinder and also a 1986/7 60hp that is complete and is said to run but runs rough and is not quite as clean. Either can be had for a couple hundred bucks.

 

[bonz_d]

Re: Advice on 1988 70hp rebuild.

Amazing, 86 views and no opinions or ya all think I'm crazy!

 

[Faztbullet]

Re: Advice on 1988 70hp rebuild.

After looking through BRP's website I was able to determine that the cranks and piston assemblies from the 60hp, 70hp and 75hp all have the same part number all the way back to 1983. Though I also see that there are a multiple of numbers for the crankcases throughout these years. Anyone have any clue as to the difference in these crankcases? I have also noted a few changes with cylinder heads.

1983-88 60-75hp still used the 4 spline crank asyhe 82-85 70hp used the multi-spline. The crankcase difference your likely seeing is changes in bore size,block casting process. The 1986 and up 70 hp is a big bore(3.187) and the 75 hp is a small bore(3.000)

 

[James R]

Re: Advice on 1988 70hp rebuild.

Look on Ebay for a good used crank. Thats your starting point.

 

[bonz_d]

Re: Advice on 1988 70hp rebuild.

1983-88 60-75hp still used the 4 spline crank asyhe 82-85 70hp used the multi-spline. The crankcase difference your likely seeing is changes in bore size,block casting process. The 1986 and up 70 hp is a big bore(3.187) and the 75 hp is a small bore(3.000)

So I'm sure I understand is it just the 82-85 70hp that used the multi splined shaft? Because as I stated it appears that the crank part number is the same on the 70hp from 1983 -1988 and maybe beyond but ti didn't look at 89 or newer.

I know from talking with chinewalker that there was a casting process change in 86 with these blocks. So is the 70hp and 75hp pre 86 the same block? Is there a way to differenciate these blocks by part numbers?

Right now the thinking is keeping the 1988 I have and replacing the crank as the compression was very good and everything ran well. Will also need another driveshaft as that was destroyed as well as the crank.

 

[Faztbullet]

Re: Advice on 1988 70hp rebuild.

Use you 1983 75hp for parts as all will interchange...and very few $$$ will be spent.