View Full Version : !2 volt conversion...

08-21-2005, 05:14 PM
Question about 12 volt conversion: My 1955 president has a 12 volt alternator. I see only two wires out of the alternator. One goes into the wiring harness, it is a thick wire. There is a thin wire that goes from the alternator to a 'box' on the fire wall. This thin wire conects into a FLD terminal on the 'box'.. out of the other side of the 'box'is a wire coming off an Ing labeled terminal. The IGN wire then travels to a ceramic fixture. I see zero identification on the alt other than some numbers in the casting, there is NW cast into the casting.This alt looks like a Mopar shaped casting of the early 1960's. How do if figure out what kind of Alt, and electric system I have?

08-21-2005, 09:27 PM
Since this is a conversion, previously done by another owner (like mine was), I don't think anyone here can say for sure without looking under your hood very closely. I suggest driving to any reputable auto electric place (alternators, starters rebuilt, etc...). I would certainly expect them to have someone there who is competent at deciphering your setup and explaining it to you in plain English. It should be pretty simple for a professional in that field.

1955 1/2 Ton Pickup

08-22-2005, 06:56 AM
Thanks for the input, it all helps.

08-25-2005, 03:57 PM
Curt, it sounds like the conversion was done using Prestolite parts. Could be either the small Prestolite alternator as Studebaker used from '63 onward, or the "basket" style used on Chrysler Corp products. That little box is the voltage regulator.

Is that "ceramic block" maybe about 3" long by 3/4" square, held to the firewall by a metal band about its midsection? If so, it's the ignition resistor, and one end of it would be a satisfactory place to connect the "IGN" wire from the regulator.

I expect the wire going into the harness makes it's way to the ammeter, if there is one on a '56 Pres.

Gord Richmond, within Weasel range of the Alberta Badlands

08-25-2005, 06:50 PM
The ceamic resistor has not a metal band in the mid section, it has a screw holding it to the fire wall. The wire from the voltage regulator to the ceramic resistor conects to the top of the resistor and at this conection sends a wire into the harnes. At the other end of the resistor a wire goes to the coil. This is a 12 coil with the other side of the coil ( again a small wire) going to the distributor. Any coments are welcome. Thanks for the infromation and chat.

08-26-2005, 05:03 AM
That resistor is just a ballast for your coil. you probably still have the stock coil I bet. If you have a newer starter solenoid you can install a bypass wire to give the coil full voltage when cranking the engine for quicker starts.


55 Commander Starlight
62 Daytona hardtop

08-27-2005, 08:01 AM
Why is a 12 volt coil getting current from a 12 volt aleternator through a resistor? Do 12 volt coils use 6 volts?

08-27-2005, 10:56 AM
The resistor used on 12volt coils is to effect a stabilizing of current demand over a range of temperatures. Thus protecting the points from oxidizing during times of low ambient temps or slow driving.
And - NO - I didn't know this off the top of my head. I too, was curious as to why resistors were used and I looked it up in an automotive text book.:D)

Miscreant at large.

1957 Transtar 1/2ton
1960 Larkvertible V8
1958 Provincial wagon
1953 Commander coupe
1957 President 2-dr
1955 President State
1951 Champion Biz cpe
1963 Daytona project FS

08-27-2005, 03:05 PM
Mr. Biggs, thanks for the information. You have a better reference book than me, thanks for taking the time to reply. But how does a 12 v coil get a better spark if it runs off six volts?

08-27-2005, 03:51 PM

Many 12 volt coils are actually 6 volt coils[:o)] (Or maybe 8 or 9 volt coils, if you want to nitpick.)

If you look at the label, providing it's still legible, you may see "use with external Resistor". Coils in most 12 volt Studes are so marked, if I remember right. Usually you will find a wire from the starter solenoid to the coil (+) terminal that bypasses the external resistor when the engine is being cranked. That gives you a little more juice for the spark at a time when system voltage is pulled down by the heavy load of the starter motor.

There are also 12 volt coils out there that contain an internal resistor, and they are used in applications without the cranking bypass arrangement.

If I remember right, from about 1958 on, Studebaker used a PINK resistor wire from the ignition switch to the coil. It's a special wire with the resistance distributed over its length. The discrete ceramic block was used only for '56 - '57 models. It is also the obvious solution for converting a six volt car.

Gord Richmond, within Weasel range of the Alberta Badlands

08-27-2005, 05:25 PM
Gord, thanks for the information. Happy Studerbaking.