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12v coil

S

Sparky70

Member
Once converted to 12v, is there any technical reason to run a
ballast resistor or a 12v coil with an internal resistor. 6v coil
removed. Thanks to all, M purring great and starts right up in
cold weather.
 
As I understand it, you have 2 choices:
1. Run a 6-volt coil with the ballast resistor
2. Run a 12-volt coil with an internal resistor without a ballast resistor

But no ballast resistor with a 12-volt coil that has an internal resistor.

If this is not correct, I am sure I will be corrected - it won't be the first time I have been wrong!
 
Not sure what your asking here. If you have a 6 volt coil you need the ballast resister to help point life and also to keep from burning out the coil. Or use a 12 volt coil that say NO external resister needed. By the way it does not have an internal resister it is just wound different.
Now if your asking which is better well 6 to 1 half dozen to the other or in other words both work the same but the 12 volt coil removes a part so less likely to cause a problem due to a part going bad
 
> But no ballast resistor with a 12-volt coil that
> has an internal resistor.

Internal resistance, to be precise. 12 volt coils are wound with finer wire than 6 volt ones so that the resistance of the coil is roughly equal to the sum of the resistance of a 6 volt coil and a ballast resistor. The effect is the same as if there was a resistor in there.
 
One converted to 12 volts, the choices are:

1) Keep the old 6 volt coil and use an external series voltage dropping (12 to 6) ballast resistor.

2) Use a full true 12 volt coil (some call internally ballasted, although there's actually NOT any discrete stand alone resistor hidden away inside lol)

One advantage of a 6 volt coil plus an external ballast, however, is the ability to use a start ballast by pass circuit, so when cranking the coil sees un ballasted battery voltage for potential improved starting especially if its cold.

John T
 
Old,
apologize, wrote my posting as I was headed out the door. Converted my 300 to 12v a few years back. I have no ballast resistor, just a 12v coil. I am suspecting the coil (HV side) may be faulty cause when I try to start in the am it will run very briefly then shut down just like the ignition was turned off. Ran all the checks, 12v on the coil, points, condenser, rotor and cap all new, switch and wiring good. I do have spark from the secondary to iron, but it is kinda yellow/orange and battery full charge. Ohm meter says primary windings look ok. Late last night I could not see fire at number four plug when removed and grounded. When the rain passes I will check the plug wires and with the spark tool see what it looks like at the coil and end plug wires. Thanks for the info on 12v coils, did not know there was different types of wire that present resistance.
 
Thanks all for info on the coil, know for further tests when the rain quits. After this 16 inches of snow we will have a mess.
 
One thing you need to check is that you have a spark at the points that you can both see and here. Carefully open and close the points by hand and make sure they have a spark there. No spark no spark from the coil either. Another way to check things and no test tools needed if take the ignition side wire off the coil. Turn on the ignition and then put the wire back on and off a few times. You should get a spark at the terminal when you tough it and when you remove it and also should have a spark from the center coil wire at the same time with the points closed. No spark your points need to be cleaned and now days it is common to have to do that to new points
 
Thanks, should have warmer weather tomorrow and no rain. Will get on it straight away. I think I took the cap off last night and the point were sparking, albeit when I checked the gap it appeared to be a little wide. My instincts still tell me there is a HV problem, guess we will see. Thanks
 
Well she is running. Replaced everything in the secondary. Ran tests per Old and Jims sheet, test light pulsing on distributor side, picked up a spark test and good blue spark at plug wires. Would not run so I pulled plugs. They smelled some gas but not allot. So I squirted some gas in cylinders and after some coaxing she runs fine. I am kinda stumped, not sure what I fixed but at least I know my ignition is in good shape. Thanks for all the help
 
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