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TOPIC: Supplying 12v to HEI distributor

Supplying 12v to HEI distributor 16 Jul 2017 01:24 #1

  • doublegimp1
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Hi all, I am replacing my points distributor on my 86 OMC Cobra 5.0l with an HEI marine version and need to feed it 12v power eliminating the resistor wire. What I see on the boat matches up with what I see on the wiring diagram with one purple and black wire and one purple red wire going to the + side coil. From searching I've found a couple different views and I'm a little confused. Is the purple/red wire the resistance wire? It feeds back to a splice and then the alternator. Also, if I simply eliminate that wire, meaning connect to the alternator wire pre-splice will that suffice to feed 12v direct to the distributor? I am assuming I will need both that wire and the purple/black wire that goes back to the starter to feed power depending on starting/running. ESA system has been eliminated and wired like a merc, I am hoping that will work on an hei distributor as well but haven't gotten there.

Thanks in advance.

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1986 Bayliner Trophy 2160 Hardtop
5.0l Chevy/Cobra
Lake of the Woods, MN

Supplying 12v to HEI distributor 16 Jul 2017 07:08 #2

  • Pcpete
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Welcome! Great question! According to this: www.google.com/search?q=omc+cobra+5.0+wi...imgrc=Yde_ooInihzXTM :
It looks like the purple & red wire is the one you are after. Getting rid of my points on my last boat was a great move. Now, get a coil that gives a bigger zap to go with it. I'm thinking a coil that's made for eight volts may not do well for long if it's being fed 12 volts.
Please add your signature and have some stuff in it like the area where you live and use your boat so possibly we can suggest a good local source and what your boat is and the propulsion system. I really helps folks help you or ask your advise.

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P/C Pete
Edmonds Yacht Club (Commodore 1993)
1988 3818 "GLAUBEN"
1980 Encounter Sunbridge "Misty Blue" (Sold)
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Boating on the Salish Sea since 1948
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Supplying 12v to HEI distributor 16 Jul 2017 14:47 #3

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So simply replace the resistance wire with a "normal" full sized one? That's easy enough. I'm guessing there has to be a resistor somewhere in this wire but since it runs under the engine I can't see the entire run. I don't think there isbthe option to run 8v to this distributor, I don't think the electronics would like it.

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1986 Bayliner Trophy 2160 Hardtop
5.0l Chevy/Cobra
Lake of the Woods, MN

Supplying 12v to HEI distributor 16 Jul 2017 16:04 #4

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In old cars there was a ceramic block called a ballast resister that is easy to spot. In the '70's someone figured out how to build the residence into a single wire. Your ignition in the start position provides 12 volts, but switches wire routes to the residence wire in the run position. It's a dedicated wire so only the coil is affected.

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P/C Pete
Edmonds Yacht Club (Commodore 1993)
1988 3818 "GLAUBEN"
1980 Encounter Sunbridge "Misty Blue" (Sold)
MMSI 367770440
1972 Chevrolet Nova Frame off Resto-mod in the garage
Boating on the Salish Sea since 1948

Supplying 12v to HEI distributor 16 Jul 2017 19:36 #5

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Ok, while I haven't fired it up yet, I did decide to say the hell with all current ignition wiring and ran a dedicated line from the ignition switch to the + on the distributor. After eliminating the resistance wire I was only getting 10v, not sure if that was due to just the wiring in the system or if something else was in play but I had 12v at the ignition switch and have it at the terminal for the distributor. FYI, not telling anyone here something they don't know but running wires in a boat sucks. Now for plug wires, new plugs, timing...then kill some fish

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1986 Bayliner Trophy 2160 Hardtop
5.0l Chevy/Cobra
Lake of the Woods, MN

Supplying 12v to HEI distributor 17 Jul 2017 07:32 #6

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Changing to a hei, you need to change out the esa module.

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Be good, be happy, for tomorrow is promised to no man !

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