1974 500 50HP Internal wiring, how many wires

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cory13

Cadet
Joined
Aug 6, 2008
Messages
15
I've kind of hit a snag with the internal harness for the motor. It has the classic rotten wires and corrosion through out the internal harness, I've already done a chop job once a few years back and cut the wire back to good but now the brittle wires and shorts are back so I figured I would just replace the whole thing the right way this time. Ordered the part from boats.net really good price too. Part number was 12-52770A1 price was $48 and a quicksilver part at that. Anywho - I got the new harness went out to the boat, pulled the cover, started to match up the wires, new harness 6 wires, Rectifier x1,soleniod X2,choke x1,switch box x1, starter x1, golden right. Wrong :mad: I looked at the old one its got seven wires it has two to the rectifier, so what gives. both harnesses only have six prongs at the plug, two large, three small on one side and one small on the other. I can't tell what the old harness colors are due to my prior chop job and the new rot. I also have not pulled the old harness yet to check what prongs run with what wires. My guess is that the second wire to the rectifier is for the tach as that was an optional peice of equipment, I do have one so if that is the case can I just splice from the one that runs to rectifier anyway. Splice it to the other location on the rectifier? This doesn't really sound right to me, but the six prongs thing threw me a curve! :confused:

On a side note what does the rectifier really do????

Motor has a serial number of 4076599

Thanks guys for your help!!!!!!!!!
 
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Laddies

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Sep 10, 2004
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12,218
Re: 1974 500 50HP Internal wiring, how many wires

The purpose of the rectifier is to convert AC voltage from the stator to DC voltage to charge the battery. There are 2 differant rectifiers used on that engine the first was a selnuim rectifer, a finned one it needs to be wired throught the switch to keep it from dischargeing the battery when not running. The later engines with the diode rectifier did not that connection and the red wire from the rectifier went to the solinoid, when the selnium rectifier went bad they were replaced with the diode rectifier, so that made the wire through the ign. switch useless and the new wireing harnesses don't have it. So if you have a old style rectifier you will need to replace it and run the wire from the rectifier to the positive post on the solinoid. Hope this is not to confusing,if so ask more questions.
 
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