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What ballast resistors should I use on my 1942 Lincoln V12 when switching to 12 volt?  How should I be checking the voltage to the coils and what reading should I be getting?

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The way I see it, original factory or new ballast resistors  of 0.8 Ohms. are  used on either 6 or 12 volt resistor coils
. Of course you need to switch to 12 volt " Resistor  Coils" when switching from 6 volt to 12 volt and not  rely on a higher ballast  resistor to reduce the 12 volt down to 6 volt  and expect to  use the original 6 volt coil.
Gerry  Richman can supply a original 12 volt  resistor coil. 
  You can use straight 6  or 12 volt coils [non ballast]  [non original]  with no resistors if you choose to.
  See post on  " Hard  Starting"   for 6 volt readings, 12 volt will be higher
. Abe @ Tom may chime in.
Simple isn't it. 

Edited by 38ShortopConv. (see edit history)
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Not all coils need a ballast resister. Check with the supplier of your 12 volt coil to see what they recommend. They should be able to tell what voltage to expect at the input to the coil.

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  • 3 weeks later...

When I first acquired my Lincoln, I didn't want to buy a 6 volt battery as I knew it would be a long time.  What I did was measure voltage at coil, should be 2.5-3 volts when running.  Be careful of fan.  I found a 1.2 ohm resistor in series with the stock ignition resistors worked about right to get it running with a temporary 12 volt battery.  I used a 25 watt, 1.2 ohm resistor which got quite warm.  I think 50 watt would be better.  Mount the resistor some place where the heat won't cause a problem.  You can also have coils re-wound for 12 volt operation.


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