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I was looking at a 1937 120 Packard sedan on ebay that had been converted to a 12volt system, which voided the function of the clock, radio, fuel gauge, and fog lights. Is there any way to restore the function of those items without going back to the 6 Volt system?

thank you
Garrett Meadows

You can use resistors for some things but those are a bit problematic if you don't have a good idea of current required. Too little current thru the high wattage resistors usually sold for motors doesn't drop voltage much and too much will still burn the resistor up. Proper size resistors have been used on instruments as have other methods. If the car has been converted to 12v negative ground, there are Runtz modules which will work a single gauge but gets expensive if more than one is needed.

If 12v bulbs can't be found or adapted for the fog lights then those, the gas gauge, the clock, heater etc would benefit from a 12v to 6v reducer. but in using a converter or reducer the wiring would have to be separated so the intended items get the correct voltage.

Thank you for the helpful and informative response. I'm a purist and would have to have the radio, clock, fog lights, and especially the fuel gauge--for practical reasons--in good working order. I can't imagine trying to drive a car without a functioning fuel gauge. I'd be in state of constant anxiety.

The car is located in California. If you get a chance and are perhaps a bit curious, go to ebay motors and take a look at the Packard. It's beautiful. Although, I can't tell if it is a 120-C or 120-CD. Perhaps you can tell.

kind regards
Garrett Meadows

Very pretty car. I think it's a 120C but 1937 isn't a year I'm real familiar with. If it was a CD would Packard have stamped a "CD" following the 1092 model number on the data plate?

P.S. The car is located in Dallas.

Yes, the car is in Dallas and I know the car if you have any further questions. DAF

I've been told that Ford gauges into the '80's used a voltage converter module that would likely work for the Packard gauges. I will be researching that some more to figure out the correct parts needed.

The 12V 1955 Packards used a Ballast resistor on the firewall to supply 8V to the instruments, which were basicall 6Volt instruments. In converting my 1938-120 to 12V, I used the ballast resistor from a japanese ignition coil to provide 8 volts to the instruments. 8 volts is near enough to the normal generator charging voltage for keeping a 6 volt battery ( 3 cells @ 2.5 volts per cell) fully charged.

PT

Take a center tap off the battery for all your six volt needs.

The 12V 1955 Packards used a Ballast resistor on the firewall to supply 8V to the instruments, which were basicall 6Volt instruments.

I hate to disagree but the ballast resistor on the firewall is for the coil. The instruments used a voltage regulator behind the cluster. It is a thermal pulse type regulator providing short bursts of 6 or 12v to the instruments. The duration of the pulses are determined by a set of contacts which are opened and closed by heating a bimetal element in the regulator. The element heats, bimetal bends and closes contacts to provide voltage out and at the same time breaks contacts providing the voltage to the element so it cools and contacts open again. The cycle repeats. Because of the pulses, the average voltage output to the instruments works out to around 5v.

Different regulator for 51-3 but the 54 6v cars used the same regulator as 55-6 12v cars to provide the 5v. The only difference in operation is because there is less voltage to control, the pulse duration is longer for 6v cars.

Since the 51-6 instruments are also thermal, the needles do not respond fast so the pulses are not visible. Some of the older gauges (35-??) including the one in question are magnetic and would not work with this type regulator. I believe Ford used the same type for some of the time but there are some solid state conversions to eliminate the contact type regulators on the market which put out a constant 5v.

A ballast resistor could certainly be used and may not be a bad idea.

For anyone who is interested, here is the inside of the 51-6 regulator plus the output for a 12v supply as viewed on an oscilloscope. With the 12v supply, pulse duration is approx 100 mv or 1/10 of a second.

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Thank you for clarifying the location of the car. I confused it with another Packard located in California.