Classic/Antique Car Repair: 6 VOLT POSITIVE GROUND, 1955 plymouth belvedere, motor horn

Question
I JUST BOUGHT A 1955 PLYMOUTH BELVEDERE. HOW CAN I TELL IF THE SYSTEM WAS CHANGED TO A NEGATIVE GROUND. IT IS HOOKED UP AS A NEGATIVE GROUND AND IT DOES START AND THE HEADLIGHTS WORK.

Answer
The only thing that needs to be changed for safety is the voltage regulator.  Take a look at it to see if it is marked as to polarity.  If there is no marking, I'd replace it to be safe, because if someone switched the battery cables without changing the regulator, this could cause a fire under the hood if the regulator points stick shut, burning up the generator and the wires.  The only other part on the car that should be changed is the coil, but that will only make the car hard starting if it wasn't changed - it won't damage anything.    The generator may or may not be charging - you can tell if you start the engine and let it idle, then lift off one of the battery cables - if the engine keeps idling, you know the generator is providing the current for the engine, so it must be working OK.  The other electrical items in the car (starter, heater motor, horn, lights etc.) don't care about polarity.  The ammeter may read backwards (if your car has an ammeter) but you can correct that by swapping the wires on the back of the gauge.  You can test to see if it reads correctly by turning on the headlights with the engine off - if the needle moves toward discharge, it's right - if it moves toward charge, it hasn't been changed over yet.

Most likely, the previous owner just did not realize it is supposed to be positive ground - if you want to put it back right, you can do that easily, especially if the coil and regulator are still the original parts, but you will have to "polarize" the generator for the right polarity.  You do this by connecting a wire from the battery "hot" terminal to the generator armature terminal momentarily - it will make a big spark, but that won't hurt you or the parts!

Dick