Hot Rods 6 Volt clock install

I am installing a NOS electric clock (called auto-wind) in the dash of the 48 Plymouth I am working on and converting to a 12 volt system. Does this clock have to have a positive ground or can I run a 12 volt to 6 volt reducer with the current normal negative ground?

 

If you swap polarity you will let the smoke out.

If you run a positive ground electrical item with a negative ground, you will let the smoke out.

Electrics do not work when the smoke is out.

 

If the Plymouth was originally positive earth, you will only get that clock to work if you have +6v on the case. If you can make a plastic (or any insulator, bakelite, timber) surround for it, you can then wire the case to +6v, (as it will no longer be grounded to your 12volt system), through a suitable dropping resistor or 6v regulator, via a fuse. Your normal supply (which was -6v) to the clock would now be fed by the vehicle ground. (-12v)

 

Since most clocks work with a solenoid to wind the mainspring, the clock might just work with reverse polarity feeding it. Easiest way is to take clock and wire it to 6 volt battery with the + going to the lead and - being the ground. Put a 5 amp fuse in series with the + lead, just in case it does not like the polarity reversal. If it works with reverse polarity, then just find a way of reducing the operating voltage to 6-8volts.

 

My 49 Dodge clock had been working fine on - ground 12v for a few years. Just winds a little faster.

Option 2: I have heard of people swapping the guts with a cheap battery operated clock.

 

Polarity doesn't matter and it will run on 12v with no problems, positive ground or negative ground wont effect it, the winding mechanism is just an electromagnet triggered by a set of points and since it was designed to run on 6v means the wire used in the windings are heavy gauge so they'll just produce a stronger magnetic field when run on 12v, kinda like running a 6v starter on 12v. You will hear a louder thud though when the clock winds itself on 12v as opposed to 6v. The clock in my plymouth has been running on 12v for about 2 years now with no problems.

 

A clock knows no voltage, only time. Mine has worked for years.