1969 omc 120 wiring harness with omc 140 motor

Andyman54

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Jul 31, 2017
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Hey all in my boat i have a omc 120 wiring harness, I am switching the motor that was in there with a newer 1970s-80s omc 140 the guy i bought it from also gave me the wiring harness for it.

Upon a brief examination I have noticed the wiring harness in my old boat are rectangle connectors for the old engine and the new engine has the more updated circle ones. I am trying to locate two good electrical diagrams for the motors.

Should I take the old connections from my old motor and transfer them over to the new?

has anyone had any experience with this?

Thank you for the help!

Andy

I just checked the motor and the numbers on the engine read 2770087 349 83

below that it say GM made in mexico.

So maybe the engine is an 83? I checked everywhere else there is no other numbers that are important, I read that the name plate would be by the distributor OR above the starter mine had nothing. ( there is a serial number on alternator ALK 6210 7A and a number on a part of the exhaust manifold 970360.). I realize thats just a standard GM block after more research and those numbers probably don't tell us anything..
 
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Scott Danforth

Grumpy Vintage Moderator still playing with boats
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Jul 23, 2011
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Should I take the old connections from my old motor and transfer them over to the new?

yes.

wiring between the two motors will be the same. purple wire to ignition a few gauge wires, etc. the connector is what connects the motor to the rest of the boat. so either convert your boat over to wiring that has the newer style connector, or convert your motor over to the older style connector.

and all 3.0's are made in mexico
 

Andyman54

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Jul 31, 2017
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Thats PERFECT exactly what I wanted to hear! Since thats the case I will just convert to old style since its easier. Thank you so much
 

Andyman54

Cadet
Joined
Jul 31, 2017
Messages
12
Okay so i am the process of moving over the wiring harnesses and i have ran into 2 main problems. The photos will show more detail.

I was able to convert the first part of the wiring harness to the new motor it was pretty much the same. But the bigger part of the wiring harness is much more different.

It has things its connected to that the other motor doesnt even have. Maybe its missing? or is it supposed to be gone?


The old motor has one more solenoid attached to the harness and it has a regulator and i cant seem to find the 3rd or the regulator connected to the other motor.

I just did find the regulator it was sitting up on the top of the motor unbolted. but the starter assist solenoid is definitely not there.



Shouldnt I just take that solenoid off find a new spot for them on the new motor?
 
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