Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

[DEERSLAYER2000]

Can I replace my old coils on a 1978 115hp evinrude with newer ones from a 1993 140hp? Thank you if you can answer this? I have a 1978 evinrude 115hp. It was was rebuilt and bored to a 140hp. The reason im asking this is that the motor runs rough and won't idle smooth.

 

[Chinewalker]

Re: Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

It's likely the reason it won't idle smooth is that the "rebuild" screwed up a good motor. There's no way to "bore out" a 115 to a 140 - they're the same bore. If your motor doesn't have a bubble back exhaust between the cylinder banks, it's still a 115. Boring the block to repair damage is done all the time and all it does is return you to the rated power - it does NOT give you any appreciable gain in horsepower.

Also, make sure it has the correct jets in the carbs. Someone may have added "larger jets" - another urban myth to adding power and another reason why it won't idle.

To answer your initial question, yes, you can probably use the later coils on the earlier motor if you can work the wiring. Later coils will have different connections.

 

[DEERSLAYER2000]

Re: Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

Thank you chinewalker I should have left it alone, I went ahead and used them and it didn't work like i hoped. They have the same wires so the other motor must be an earlier model. the coils were given to me and they looked better than the ones I had and since you say the motor is not a 140hp ( i didn't know, just going off what the guy that gave me the boat said) I thought it would help. Now I have a problem that the motor wont run now, it has fuel and spark and it just turnsover and backfires. What would i have done to the motor just changing coils? I put the old one back on and didn't change. The motor ran fine all last summer and 2 weeks ago except the rough idle.

 

[misery]

Re: Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

do you have your plug wires on correctly?

 

[daselbee]

Re: Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

What misery said. Backfiring indicates an ignition problem, very commonly caused by plug wires OR the orange PP to coil leads being mis-wired. I saw that exact issue on a 1979 140. Look at the orange wires from the PP to the coils. They should have a colored stripe, likely bleu and green. The orange/blue goes to the top coil, the orange green goes to the bottom coil on each bank.

 

[DEERSLAYER2000]

Re: Can you replace coils from 1993 140 hp evinrude to go on a 1978 115 hp evinrude

Thanks guys.. The wires from the coils go into a female plug that male plug from the power pack connects to. Did't mix those up