backrodebob
Member
QUESTION? 12 v system, external 1.5 resistor with 1.5 coil or 3.0 coil pros cons or personal preference? some say 3.0 gets hotter? true or not?
coil
- Thread starter backrodebob
- Start date
JSeery
Member Emeritus
The 3.0 ohms coils are easier to install, but there are advantages to a resistor + coil setup. That is why Ford used a resistor with the original 6v coils. The resistor varies the resistance as it heats up, so there is more voltage going to the coil at startup. If you really want to go whole hog, add a later model starter solenoid. This is the arrange Ford used on the later 12v vehicles. The solenoid setup bypasses the resistor for full battery voltage to the coil while the starter switch in engaged. As soon as the switch is released the coil voltage is dropped down by the resistor.
rotorwrench
Well-known member
If all is working well, the coil will not increase in temperature all that much and even if it does, the modern coils generally use an epoxy internal insulator instead of tar like the old coils did. When the coil is in operation, the magnetic field is getting broken multiple times per second. They only get hot when the points are closed and the ignition switch is on when the engine isn't running as a general rule. Now if something is wrong inside the coil like a cracked primary winding wire, then the resistance of the primary increases and that can lead to overheating. Eventually the coil will cease to function if the primary is damaged.