54 Plymouth 6 voltage system to a 12 voltage system

Hi there I am buying a 54 Plymouth and how hard is it to convert from a 6 voltage system to a 12 voltage system??

There are some things you can get by with. The older "wound field" motors, unlike modern permanent magnet motors, "don't car" about polarity. This means blower motors, wiper motors, and the starter will still turn properly regardless of ground polarity

A 6V starter does OK on 12, the solenoid is a different matter

For gauges, you can but a device called a runtz..........

You may need one for each gauge they are used on
Speedway Runtz 12-Volt to 6-Volt Voltage Reducer

For 'lectric wipers and heater, either change the motor or get proper dropping resistors. You will need to measure the operating current at 6-8V to figure the proper resistor

These "volt drops" have been around for decades at parts stores. I forget, I think they handle about a 4A load. You have to add more in parallel or series-parallel combination to run more current



Coil, use a 12V coil, either one made for 12V direct, or one like the Mopars here use with a ballast resistor

Charging system, you'll either need a 12V generator and matching regulator or a 12V alternator

The ammeter you'll need to reverse the wiring on the terminals or it will read backwards

Change all the lamps to 12V

I did my 55 Dodge. I converted to 12v negative ground using a conventional alternator, ignition and starter at the same time. Inspect the old wiring carefully as it is likely old and brittle with cracking insulation.

My factory clock and radio were left disconected. The factory guages dont care about polarity but do care about voltage. As I am cheap (or live by the hotrodding spirit as I prefer) I didnt buy a fancy power supply for them. Instead I bought the largest capacity (2.5 amp I think) cigarette USB adapter and hacked it. They put out a steady 5.5 to 6 volts. I cut it open and used the circuit board as a power supply for my fuel and temp guages. The wipers and blower motors were left to run on 12V. I wired the headlight circuit to operate a relay which powers the new Hella headlights. All light bulbs and the turn signal flasher were changed to 12V replacements, with led dash lights. I bypassed my ammeter to avoid having all of the current running through it.

Two years and all is good. It is well worth doing!

LOL there are lots easier ways to home build a 5V regulator than hacking a USB. Start by searching LM7806 or LM317

Motors? Are you saying you ran your 6V wiper/ blower motor on 12? That does not sound good!!

Yes, that is correct. Honestly, it is not like i drive the car in the wet and cold with the blowers and wipers running all the time. I had thought about putting a ballast resistor in their power feed to drop the voltage down to 8 - 10 volts and may do that this winter.

Yes, I know that there are other ways to build the power supply, but you can but the USB adapter at any grocery store checkout for a couple bucks. It was just more convenient, LOL.