If you are only changing polarity and not voltage then the only things that requires attention are the ignition coil wires and polarizing the generator. For positive ground, (factory) the coil wires same as battery. Positive side to distributor (ground) and negative to power. Ford radios from 6 volt era worked just fine with either ground. I had a 6 volt negative ground car in high school with a 6 volt positive ground Ford radio in it.



Tom from the chiggerfarm located in the beautiful Heart of Central Texas

When you cannot dazzle others with your brilliance, baffle them with bullcorn!

Yes, my '55 Fairlane had been converted.  Probably by somebody who didn't know that it was supposed to be positive ground.  And I admit when buying it that way, I had no idea it came from Henry that way.  The newest vehicle I'd owned up to that point was a 57 Custom.

One potential problem is the polarity of the coil.  If you find hard starting to be an issue you could need to switch the wires on the coil.  Mine had not been switched and reliably starting the car was problematic until somebody clued me in on this.  Seems the coil will only give about 75% of the spark when wired backwards in relation to the car's polarity.

When I found out the car was originally positive ground it stopped me cold from doing anything, I just couldn't get my head wrapped around sticking the positive lead to the block and it not blowing stuff up. When I heard the term polarity sensitive, I got to where I was comfortable with the system after that. On this car the coil is wired the same as the battery, neg leads to the distributor and the battery is charging when the car is running so that system is running right and Im not gona mess with it right now. After deer season Ive got to get the rear oil leak fixed, get some manuals and start on the motor. Thanks for helping me with sticking the positive lead to the block is really ok.

FYI.  When I purchased my 55 Tbird, I discovered a previous owner had already converted it to 12 volts but they left the ground positive. After much consternation, I decided to switch to a negative ground.  This turned out to be no more than switching the battery cables and reflashing the voltage regulator. Everything worked except the radio.  It had been modified to work with a positive ground, so I disconnected it.  If you wish to keep your car stock, I can appreciate that.  If you convert to 12 volts, know that your 6 volt starter, generator, O/D solenoid and most everything else will work.  Six volt electronics use much larger wiring and are very robust. My horns are still 6 volt and they are now very loud.  The biggest problem with six volt systems these days is getting anyone to work on them.  Years ago, there was an auto electric shop on every street corner.  Finding one now is like hunting for Unicorns.

Phew thanks dobie, Its the ground wire going from the od relay to the block, Ill post a pic tomorrow, Thanks again I really appreciate your knowledge

If it's working and you're happy with it you can leave it as is. Suggest you replace the wire going from the relay to the coil if the insulation is deteriorated. That's part of the kickdown system; it grounds the ignition for about 1/2 a revolution when you hit the kickdown switch to remove driving torque from the OD so the solenoid armature can withdraw from the drive plate. If the insulation is gone you could get unwanted grounding from the bare wire contacting metal. There's no current on that wire, it's just a ground.

yes I did and the overdrive worked, I didnt try the high speed kick down prob wont use anyway. So I can leave like it is or what is your recommendations?
and what about the od relay wire that is missing insulation? Guess I can fire her up like it is and see if that wire is getting hot?

The OD is not polarity sensitive.

It's not a real problem to run a 6 volt negative ground system. Usually, gauges are not polarity sensitive and if I remember correctly the temp gauge is right - hot with no power, cold when first giving it power.. Stock radio could be a problem with negative ground. Starter is not polarity sensitive. Not sure about polarity  on an overdrive. (if you have it).






54 Victoria 312;  48 Ford Conv 302, 56 Bird 312
Forever Ford
Midland Park, NJ

The relay on the firewall belongs to the OD. When you test drove it did you try the OD?