Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks


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#478633 02/08/23 02:17 PM
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I know this has been addressed many times but couldn’t find the old threads prior to 2020. I am rewiring my 38 wire at a time and need a wire chart for wire gauges. I thought wires were mostly 16 gauge but gent from ynz said there are 14 gauge wires in the headlight circuit as well as 10, 12 and 14 gauges used elsewhere. Any suggestions again as I posed these questions when I did some rewiring on my prior 38?
Thank you
Michael
38 Master Sport
PS. Be nice if the wiring diagram had for each conductor

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It begins, I removed the light harness except for the rear tail/brake light. The wire insulation was so brittle that a hot wire shorted to ground causing a puff of smoke from under the dash. Some of these wires are large gauge for sure like 12 or 10. Someone said most wires are 16 gauge, but i can't tell just looking at them. I bought a wire gauge to check size hoping that will help but i will review circuits to make sure the wire will carry the amperage while my 38 is 6v. i am going to record my findings for future reference in the event someone is looking like myself.

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Wires running to lights are usually 16 amp.


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solafide,

That harness is in about the same condition as the one that was in my '37. I never even considered connecting a battery to the system until I replaced it.

I considered trying to make my own harness using the old one as a pattern. I quickly decided to buy a good reproduction harness after I realized how many different wire colors and gauges plus all the different connectors and coverings i would need to buy.


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. First remember that 6 volts means you need twice the amps as 12 volts for the same watts. Then look at this web page. <http://home.znet.com/r1937/12Volt.htm> All wires are a different gauge depending on the load they must carry. The National Electrical Code (NEC) rates what size gauge for what amps. I've purchased 3 wiring harnesses
from 3 companies and was dissatisfied with all. None would incorporate extra wires necessary for turn signals. Two did not have cloth covering and the third wasn't long enough. Don't use Lithium grease with electricity.
I bought a Superior bus that someone had wired all in 18 gauge. Orange headlights, Etcetera! .
. .

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This diagram doesn't specify wire gauges but it does show which circuits are heavier gauges by the thickness of the lines. If the lighter circuits are 16 ga you can step it up as necessary from there.

http://chevy.oldcarmanualproject.com/electrical/wiring/pdf/38wiring.pdf


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I am re-wiring a 41 with my sons. It is not a show car so we are using modern insulated wire. If you do your own make sure that you are getting 100% copper wire. Use a trusted brand. We ordered some off of Amazon and it was copper coated. Returned that. Southwire makes a good selection of wire. Make sour the insulation is oil and abrasion resistant.

Just as important as the wire are the connectors you are using. They too should be copper. I bought some that claimed to be tinned copper. Cutting one of them reviled they were silver inside. There is allot of cheep junk that will dur the job short term but would not trust in a car.


I have found that having an old car is a constant project that is never done. I think that is a good thing. Keeps me learning new things. Having two from different eras is just a form of higher education.
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Thats a good observation, the long conductor to the headlights look like 16 gauge so the larger are 14 and 12 and possibly 10. I have a wire gauge to check wires. I'm going with cloth covered teflon insulated conductors from either YNZ and or Rhode Island. I'm not trying to follow original color specs but original style with my own twist. I do plan on adding many accessories but all after i convert to 12v.
Thank you for the reference, I save it

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If you are converting to 12 volts the wire gauges can probably be one size smaller and still work very well. Is the 6 volt system not working as expected.

Last edited by Rusty 37 Master; 02/15/23 11:58 PM. Reason: Spelling

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All conductors in the engine compartment are mostly bare wire due to the brittle insulation falling off. I replaced ignition with modern equivalent gauge but all lighting needs replacement and I will redo ignition with period correct looking conductor as soon as I know what to order. A lot going on so rewire has been a low priority

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Converting to 12 volt is in the future, I will roll with 6v for a while

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solafid

I contemplated rewiring my 1938 Coupe, after doing research through books that I had, I found it was not worth the headaches.
I think from experence that you are going to be money ahead my buying a new harness.
I ordered a new harness, I think that it was ynz. The person that help me install it had over 30 years wiring cars, he was not happy, the wires near the light switch were 1/2"-1" too short. It was a struggle.

Good Luck

Last edited by timbeilby; 04/18/23 10:04 PM.

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