1938 Dodge comes home

Picked up the dream car on Wednesday.No more '60's low riders.This five window has the original six cylinder and three speed.A real time capsule.I would like to update the electrics and start driving.Do I have to do a complete wiring harness to switch to 12 volt and negative ground?

 

As the wires are probably original the are cloth covered and dried out. A new harness may be the best idea. Six volt wiring is actually larger sized then 12 Volt so the problem is not wire size but wire condition.

 

Nice work! I love the '36-'38 Dodges, very nice looking cars.

As '39 Ford said, the 6v wiring harness itself is actually heavier gauge wiring than a 12v system, so its more than capable of running 12v if its in decent condition. Now, if its really original, it probably isn't in decent condition, and cloth wrapped wiring tends to lose the cloth covering and leave bare wires.

Also, you'll need modify more than a few things. All the light bulbs will have to be changed to 12v versions, the 6v bulbs won't last long at 12v. Also, your amp gauge will need to be unhooked or modified. Its set up for positive ground and 6v, and you won't like the results if you hook it to 12v negative ground. You'll have to look into the heater motor or windshield wiper motors if your car has either, as they will need to have ballasts to step them down to 6v, or be upgraded to 12v versions. The starter motor will likely be just fine (and it will even spin faster!) since its used in such short bursts, but the solenoid may not last as long.

That's most of the stuff that causes issues, but might not be everything. After all that, it may be easier to just get a new harness to keep things straight. But you'll still need to deal with the stuff that stays, especially the amp gauge and anything that uses electric motors.