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I have a question for the experts out there.........

I have started the conversion of the my 1949 Super 8 Deluxe (2372) from factory 6V Positive Ground to 12V Negative Ground to make starts easier and more drivable.

I have stared the process with getting a generator from a 1956 Clipper (12V Positive ground) and having it rebuilt (new bearings, windings checked, new brushes, glazing removed, etc). I also know that the following things will need to be addressed: New 12V coil, all 6v bulbs replaced, heater blower motor replacement, R11 Overdrive solenoid (currently not functional), and radio.

I have started building a +12V stepdown to +6V electronics so that the factory Philco radio can be maintained (Using the 1950 Custom 8 wiring diagram manual). My question is, the factory radio appears to be Positive ground chassis with a fused input. The diagram in the manual (https://www.packardinfo.com/xoops/html/downloads/1950_CustomRadioOM.pdf) lists an input voltage of 6V +/-A. Does this allow for the input voltage to be "inverted" from Positive Ground to Negative Ground without damage to the radio? I do not want to destroy anything more in this conversion process.

I understand that this voltage conversion may be seen as blasphemous to some traditionalist Packard Owners. I would like to keep the vehicle as close to original as possible; although, make it a bit more drivable.

Anyone whom may have already performed this type of conversion, please feel free to reach out to me and let me know what else that I may be overlooking. I welcome any advice that the Packard community may have for me.

- Eric Hansford
1949 Super 8 Deluxe in Egyptian Sand / Egyptian hood ornamemt.

56 generator is negative ground.

dont forget about the gas guage and any other electrical gauges that are running on 6 volts.

heater motor may not matter if you can get something that takes 12v to 6v and handles alot of amps.

The stock 49 radio will work with negative ground. If modified and the vibrator has been changed to a modern solid state replacement or any other solid state conversions such as FM, Bluetooth etc has been done then it will be damaged if polarity is switched.

When doing the OD solenoid conversion don't forget about the relay. Instead of the expensive original looking R11 repro you can use a modern inexpensive 30 amp Bosch type cube relay. If the original relay is shot the guts can be removed and the Bosch hidden inside the can but if the original relay is still good it would be nice to save it as ebay material for someone looking for a 6v original.

You can buy a dropping resistor similar to this onehttp://www.fifthaveinternetgarage.com/electrical_parts.php for the heater motor. Place it in the wire feeding the heater switch and it will work well on that application. Just be sure to mount it solidly and in free air away from any wiring or other items because it will get hot. If stock, the heater feed wire is probably off the ign switch so inserting into the wire over in that area would work well.

You could get Runtz regulators for the instruments but it would require separate ones for gas, oil and temp so that would be expensive. If you are building your own that is fine but there are 12 to 6v converters capable of handling several amps available on ebay. They would be good for instruments, bulbs and the like but unless they specifically state it is OK, most are not for use with motors or solenoids.

Cli55er,

You are correct. The '55 Clipper generator is Positive Ground; while the '56 is Negative Ground. Thank you for catching me on this.

Howard,

Thank you for the information. I appreciate the insight. Just trying to not get in over my head on this since I am working with multiple people on this project and trying to keep everyone "on the same page".

I do not want to damage anything more in the process of this. I know that it will not be a quick switch-over; but also do not want a major catastrophe to occur in the process.

Generators do not have polarity but they must be polarized when installed whether new, used or rebuilt. Voltage regulators are 6V or 12V and are pos ground or neg ground and will be polarized when the generator is. Using a different polarity will not affect the function, it may give mildly shorter contact life.

When your car was new the only US cars on the road were 6V and they started well except in some sub zero conditions.

Fred,

Thank you for this information.

Is there anything else that I may need to look out for in regards to this type of conversion from 6V Positive Ground to 12V Negative Ground (i.e gauges, fuel sending unit, etc) that I may be forgetting?

sending unit wont matter that i'm aware of.

gauges wont matter either. just drop the voltage. either use the runtz like HH suggested or build your own. i built my own. for the price of the runtz, you can order enough parts off ebay to build like 6 of them.

i dont remember the website i found to build my own runtz...but i believe it is in my 37 blog.

i dont know if your car has a clock, but i dont see why it would hurt anything either as the clock in my 37 was just a manually wound clock that was triggered by points that snapped the mechanism back to wound. i cleaned up my clock and tested it on the bench after cleaning it and it worked fine with a negative ground. i did not keep it connected though.

12v cars have a ballast resistor in the coil circuit.
When starting it bypasses the resistor and starts on 12V. When runniung it goes through the resistor which drops the coil voltage to about 8-9 volts. You will need a relay to accomplish this.

If you run the coil on 12 v it will prematurely burn the points.

Ballast resistors are avail at auto parts stores

Lots of good advice posted above, and I would like to add one more thing. You will need to reverse the leads on the new coil from where they were on the old one. The negative (-) lead goes to the distributor on negative grounded systems. JWL

Edit: You should be able to get by with running the ballast resistor on the coil without any switching devices. The resistor, like Fred says, will drop the voltage from 12 to 8 volts or so. This should provide an adequate amount for starting.