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Part interchange

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Chevy57

New member
Good morning,


I recently purchased a 1978 Checkmate Predictor as a project. It had the original 1977 115hp Evinrude. The motor has a broken ring land on one of the cylinders.
I just bought a 1991 Evinrude 90 HP to replace the 115 because I felt like it would be more work and expense to rebuild as opposed to update to a slightly newer motor.


My question is what parts interchange between a 1977 115hp and a 1991 90hp? Lower unit? Ignition parts? How about the impeller? I have a brand new impeller kit for the 115? I’m tying to decide if I should keep the 115 for parts or sell it for parts.


What do you folks think?
 
Question for you.----The 91 model shifts to forward with an UP motion of the shift rod.----So have a look at the 77 model.----Does it shift to forward with a DOWN motion of the shift rod ??-----And all these V-4 crossflows suffered from broken rings.----Post compression values for the 91 model 90 HP.
 
I did not look at the way the motor shifted. I didn’t try to run the motor when I bought it because it had been sitting for 5 years. I took a battery, to spin it over and check compression and spark. Lowest compression was 123 psi and highest was 128 psi. I can’t remember which one was higher or lower but all were within 5 psi. Had spark on all 4 plugs. I’ll pull the carbs apart and clean them up.i have a new impeller kit for the 77 I’m hoping it’s the same for the 91.
 
I can not see or test your motor.-----The lower unit on the 77 may shift opposite to the 91 so it will not be a direct swap / fit.-----Up to you to check it.
 
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