I know a ballast resistor is supposed to get hot during low speed operation to increase resistance, but how hot is it supposed to get? With the ignition on without the engine started, mine is too hot to touch. 71 Duster 225ci with electronic ignition conversion.

 

Better keep a couple handy then. Sounds like you have some resistance on the primary side of the ignition system. 440 will chime in later on with all the details to check.

 

Too hot to touch is perfectly normal WHEN RUNNING. It IS possible that you have the wrong coil, or a damaged coil, but in the case of a partially shorted coil, a high speed miss, especially under load is the norm.

NEVER leave the key on for long periods without the engine running. I don't know on the Mopars if it will hurt the ECU, but it can burn up coils and ballasts

 

i have had one get so hot that it started too sizzle it burnt the paint on the firewall turned out to be a bad coil

 

I'll check the primary side resistance and let you know what I find.

 

I always use a longer screw with a spacer to mount it offset away from the firewall a half inch or so to help it cool. Haven't had one go bad yet.