ignition coils, whats the difference??

OldIron

Member
Hello,

I was a bit silly and forgot to turn off my ignition switch, and the 6v coil hooked to a 12v battery made an awful mess. The oil inside the Coil literally spewed up and around the whole inside of the newly painted hood, frame and engine block. Not sure how I can clean that off. Guessing kerosene might be best. We shall see... (any ideas welcome)

Add to that, when I started looking for coils, there were two options (and jeez did they go up in price!):

Internal and External Resistor.

I think I have it right, but not sure.
With the Internal Resistor, I think the coil while starter cranking puts out 12v to the points, but once started (starter not engaged) and cranking stops the coil reverts to 6v to run cooler.
Not sure how this would work with an External Resistor.

I have a 1946 Massey Harris 101 Jr RC, converted from 6v to 12v with now a negative ground.

How do I know which I need, and please explain why if you know.

Thanks for the help!!!

OldIron
 
Also wondering if this is the right type of universal ignition coil...

http://www.yesterdaystractors.com/D8JL12029A_Coil-Ignition-12V_10295.htm

Thanks again to any who might help.

OldIron
 
NO such thing as internal resister. There are 6 volt coil as in needs external resister and then there are 12 volt coils no resister needed. The difference in is the 12volt coil is made so it has more resistance to it. So yes if you got a coil that say no resister needed it is correct for a 12 volt system.
By the way I learned about the coil making a big mess but in the early 70s when I had a VW Bug and put a 12 volt battery in it but it was a 6 volt bug. Left the key on. The coil exploded and sounded like a shot gun going off and yep big mess under the hood.
As for the key switch likely to work fine.
 

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