Camaro IROC-Z V8-350 5.7L VIN 8 FI (1990)
HEI Distributor With External Coil
The distributor may have an interior, (integral) coil or an exterior ignition coil. The integral coil is mounted in the distributor cap and connects through a
resistance brush to the rotor. The exterior coil is mounted remote from the distributor and is connected to the rotor through a high tension coil wire.
The coil is a transformer which steps up battery voltage (12 volts) to high voltage (25,000 to 35,000 volts). The primary circuit is energized when the
ignition switch is in the "ON" position. When the ignition module breaks the circuit to ground, on the primary (negative side of coil) circuit, the magnetic
field collapses, which induces high voltage in the secondary circuit, which finds its ground at the spark plug.