12v Coil on a conversion
 

After cleaning up the engine bay today, I saw the writing on my coil is a 12v. The question is this. Prior to the coil, the bat lead goes to a step resistor to 6v. Why would that be? I could understand it there were 6 v to the coil, if it were a 6v coil. If they converted to 12. why step voltage down to 6 v, then put a 12v coil on it.

JimG

12v coils typically operate at about 7.5v. Ballast resistors are temperature sensitive, so you get higher voltage at start-up, less when idling. It improves point life. I assume your truck is 12v?

Yes that is true. It is a 12 v, neg grd.

You only need 2.5 - 4V to the points. Most systems use a resistor, either external in the wire between the ignition and the coil OR inside the coil and those are usually marked to indicate it has an internal resistor.

When I convertet my 55 to 12v back when I was in high school I forgot to dead with coil correctly, I burnt up a few sets of points before I figured it out. 12v to points all the time will burn them. Years later I converted a ch@#y to HEI from points and had to revisit coil power only opposite needed 12v at all times. Keep askin the questions helps us all remember what we did to keep em runnin'. Kurt G Y blocks rule.