DESCRIPTION
Dura-Spark I - This ignition system uses a solid state distributor, primary wiring, coil, and an electronic control module. Special 8 mm spark plug wires and wide gap spark plugs are used. Dura-Spark II - The Dura-Spark II ignition system is basically the same as the Solid State ignition system, with 2 major differences. The ballast resistor value changed from 1.35 ohms to 1.10 ohms and the system uses the Dura-Spark i system distributor assembly (special rotor, cap, and adapter).
Some Dura-Spark II system equipped models use a dual mode timing system. The dual mode timing system uses a 3-connector electronic control module. This connector is attached to a switch. The switch is either a distributor modulator valve, used in engines with the fuel economy package, or an ignition barometric pressure switch used in engines (or operation in high altitudes. Solid State Ignition - Used in 1978-79 American Motors and 1975-76 Ford Motor Company vehicles, this system uses a soiid state distributor and conventional spark plug wires and spark plugs. The ballast resistor has a value of 1.35 ohms.
OPERATION
When ignition switch is on, primary circuit and ignition coil are energized. As distributor shaft rotates, the distributor generates a signal that causes electronic control module to braak the primary current and induce a secondary voltage in coil. A timer in module turns primary circuit on again to energize coil for next spark cycle. Dwell varies with engine speed and cannot changed.
ELECTRONIC CONTROL MODULE
Each module uses 6 or 7 wires. The Blue wire, if equipped, is a fusible link that protects the electronic control module. The Red and White wires are ignition feed. The White wire is ignition primary circuit while engine is cranking, the Red wire is ignition primary circuit while engine is running. The Red wire contains the ballast resistor.
The primary current is turned on and off by the electronic control unit through the Green wire between module and coil. The Orange and Purple wires (Violet wire on AMC) transmit signals to the module from the distributor stator/magnetic pick-up coil. The Black/Green wire (Black wire on AMC) is the distributor ground circuit.
DISTRIBUTOR
The distributor contains a pick-up coil which produces a magnetic field. The armature, turning with the distributor shaft, causes the magnetic field to collapse. The module senses the make and break signal of the magnetic field and signals the ignition coil to turn on and off. The Solid State ignition system uses a conventional distributor and wires. The Dura-Spark I and II ignition systems use a modified distributor assembly (special rotor, cap, and adapter) and 8 mm secondary wires to provide better insulation for the higher secondary voltage.
IGNITION COILS
Each ignition system uses a different oil-filled ignition coil. The wire terminals are designed so that the interchange of the 2 types of coils is not possible. The "DEC" (negative) coil terminal connects with Green wire of electronic control module. The "BAT" (positive) coil terminal connects with Red wire (Yellow wire on AMC) to the electronic control module and the ignition switch, through the ballast resistor on Dura-Spark II and Solid State ignition systems.
SYSTEM PRECAUTIONS
A spark may occur if distributor is moved with ignition switch in the "ON" position. DO NOT remove secondary spark plug wires while engine is running.
Silicone dielectric compound must be applied to all insulating areas of distributor, coil, and spark plug boots. Coat distributor rotor tip with dielectric compound to a thickness of 1/32". DO NOT use silicone dielectric compound on multi-point rotor.
