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Discussion Starter #1
I have a '53 plymouth that is 6 volt positive ground. I would like to change it to a 12 volt. I have a GM generator that will fit the mount perfectly. I know I must change the coil and lights to 12 volt. My problem is the starter will probably run backward if I switch to negative ground. Does anyone know of a negative ground starter for the old 6 cyl. flathead. I thought of maybe creating a new generator mount so I can isolate it from the positive ground, and running the generator to the battery only using a seperate voltage regulator.
Oh the problems of trying to keep it looking stock!
 

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Old(s) Fart
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Believe it or not, the starter motor will turn in the same direction. I did the same conversion to a 1952 Allis Chalmers tractor with gas engine. 6 volt positive ground to 12 volt negative ground with a Delco internal regulator alternator. The starter spins MUCH faster. Of course you'll need to change the bulbs to 12 volt and use a dropping resistor on the instruments. The ammenter leads will need to be reversed if you have one.
 

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Doc here, :pimp:

I do not advocate running Split busses OR split polarity's at all..It's a tragedy waiting to happen! You should go for "all" or nothing at "all" as far as power.

If your upgrading to 12 volt, you may want to consider a wire kit..The present wire is 50 plus years old, Cotton insulation, that is petroleum based product saturated, that will support a flame like Det chord..

Some considerations for a 12 volt upgrade:
  • Starter : While most DC motors will run fine 125% of rated load, It will drastically reduce the service life of the motor..AND 6 volt starters are almost no longer an "Over the counter Item" at most auto parts stores..(something to think about on a road trip!) Find a suitable 12 volt motor that will bolt up OR that the snout can be changed on.
  • Solenoid, MUST be 12 volts!
  • All Vehicle lamps (including panel lamps , backups if equipped, courtesy lamps Etc.)
  • Coil
  • Horn relay
  • Horns
  • Regulator (if new alternator is not internally regulated)
  • Windshield wiper motor (if not Vacuum)
  • Heater Motor
  • Stock Radio (if retained can be problematic)
  • Instrument regulator (S) for the stock gauges (If you can't find one , let me know, I can give you a schematic for a 3 tap Linear Regulator Chip that will do the job , that you can build for under $5..)

Also, while upgrading, you may want to INSPECT all the stock switchgear..after All, it is 54 years old, and replace anything that looks like it is past runout..

Another consideration, would be employing the use of lighting relays, for brighter lamps and reduced current on the switchgear.

BE sure to install PROPER fuse links on your power feeds and alternator output..It may save your rod from burning to the ground someday!

Make sure all your grounds are properly bonded, use star and lock washers at each point, and burnish off all the old paint, dirt and grease from the bonding area.

Doc :pimp:
 

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Discussion Starter #4
I understand all of the changes that have to be made. This is not my first time switching to a 12 volt. My concern is the positive to negitive ground.
 

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Tow Chainer
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I'll be working on a similar change on my 54 dodge. Though I am also replacing the whole wiring harness and using a mopar alternator and voltage regulator.

I will be running the stock 6v starter on mine. I confirmed it spins same regardless of polarity.

On mine there is one other year that is 12 volt and matches the tooth count on my torque converter. I think it is 1956. I have a 241 v-8. I do not know if the Plymouth had a v-8 in 53 or if it uses same tooth count flywheel/torque.

There are lightweight new starters converted to fit the v-8's at again I don't know if the 6 and 8 are the same, but I think they would be able to tell you that. They are about $290, but it's a NEW lightweight starter that you could move up to later.

http://www.hothemiheads.com/transmission_adapters/starter_replacement.html
 

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Magnus_Jager said:
On mine there is one other year that is 12 volt and matches the tooth count on my torque converter. I think it is 1956. I have a 241 v-8. I do not know if the Plymouth had a v-8 in 53 or if it uses same tooth count flywheel/torque.

http://www.hothemiheads.com/transmission_adapters/starter_replacement.html
Doc here, :pimp:

MAGNUS_jAGER

Not a Plymouth or Dodge guy at all, but Desoto's had Hemis That far back, Not sure if they are 12 volt OR if they will interchange or not, but that might be a place to check..

Doc :pimp:
 

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maddogmodl said:
I understand all of the changes that have to be made. This is not my first time switching to a 12 volt. My concern is the positive to negitive ground.

Doc here, :pimp:

Then the Radio, and amp gauge would be the only other areas to check for polarity changes.

Doc :pimp:
 

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Discussion Starter #8
Thanks for all the help guys. Now that I know that the starter should go the right way, I can start on changing things soon.
 

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Tow Chainer
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Yeah you should be fine for a good long time from what I hear on those starters. I contacted a rebuilder about rewiring for 12 volt and they pretty much said don't bother unless it has issues already. If your starter was strong to begin with it should server you a good long time.
 

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Hey , Dont mean too Hi jack your post . But Im a newbie ! I have No New thread ! Or a way too post a new thread , on my Screen . <<< Ive searched ! Several time's ?

any help would be appreciated ! When I click on new post ? Just throw's me back in to today's post ? What am I doin Wrong ?

Thank's ! Sean
 

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Never had the experience of converting 6V to 12V system. Polarity change should not be a big influence for wires or anything that has a wound armature, however using basic OHM's law if your resistance remains the same by doubling your voltage you will double the amps. That will change your guage readings, double the current to the fusses etc. Tube radio will fry.
 

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MOPAR Guy
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One thing to remember: Your 6 volt started is most likely a Bendix drive. It uses rotational inertia to engage the starter gear into the flywheel. Because of the much higher speed of the motor the gear will be thrown into the flywheel extremely hard. You might try a heavier spring on the Bendix drive, or look on ebay for a 12v Bendix drive starter. (They did make them.) My dad has used both these options on a 1950 Plymouth and a 1955 Chrysler New Yorker.
 

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Lost in the 60's
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If you change from positive ground to negative ground....the starter will not turn backwards. The amp guage will read backwards however untill you reverse the wires on the guage.
 
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