The reason for the ballast was to drop the voltage and amps in the ign primary circuit so the points wont burn up to soon and to limit the current flow through the coil so it last as long as it should. Mopar still uses the ballast when they went to electronic ign but not all manufactors did as some built the coils to work with a full time 12 volt feed and they can also limit the current flow by the electronics controlling the dwell. But the ballast is a resistance put in the primary ign circuit before the main load (the coil) in the circuit. It gets hot because of the electrical resistance it puts in the circuit to limit voltage and the current flow. Its not made to be a heat sink but they put it in the ceramic because they know it will get hot enough to maybe burn someone touching it when its in use. Its just like having a loose connection in an electrical circuit that can get hot because the loose connections puts more resistance in a circuit. Think of it like a crankshaft not getting enough oil to the journals. They heat up and get hot because the resistance to turn is much more with less oil and that resistance will build heat. Look at a blower motor resister as it puts resistance in the circuit before the load (blower motor) and it can get red hot on the lower speeds when it puts the most resistance in the circuit. I am sure the engineers dont want it to get red hot but it does heat up because of the electrical resistance it puts in the circuit. It only makes sense because the only reason for the ballast in the ign circuit it to limit the current flow and drop the voltage. They dont need it to get hot but thats what it does because of how much resistance it puts in the circuit. The only reason some may have ceramic on them with fins is to help disapate the heat which is why many blower motor resisters are in the housing so it blows air over the blower resister to help it disapate some of the heat. Ron

Last edited by 383man; 03/31/17 04:03 AM.