54 Plymouth 6 voltage system to a 12 voltage system

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!