Whats the difference?

[Mr. Belvedere]

Between a 6v and 12v coil? My car came with a 12v coil that I have not changed since it appears to work fine the way it is. So what is it ? Thicker windings or more windings for the lower primary 6v car?

[Plymouthy Adams]

nothing if it is the style with the external reisitor....the industry when it went to 12 volts did not change everything over...gauges and coil are a couple items that were continued with the use of dropping resistors and CVR's. It was found that starting on 12 volts resulted in such a tremoudous spark and as it was just a few seconds burst of power..the coil could well handle the extra voltage as could the points...however continued use would eventually burn up a set of points and overheat the coil. So if you have a 12 volt coil for use with an external resistor..effectively you have a 6 volt coil..most resistors drop this voltage to 6.8 to 7.2 volt range as it is and matches well to the 6 colt charging circuit in your car. Polarity is also not a factor..it could care less...about the only thing you will visually see in the polarity aspect is the opposite side of the points pit..