Ignition System: XJS

The Lucas Constant Energy Ignition system includes a breakerless distributor, amplifier module, 2 ignition coils, ignition switch, and battery. No ballast resistor is required.

The distributor has conventional centrifugal and vacuum advance systems, an anti-flash shield, rotor, reluctor, and pick-up coil. The reluctor is a gear-shaped component with 12 teeth, one for each cylinder.

The pick-up coil includes a winding, pole piece and a permanent magnet. A 2-wire shielded harness connects it directly to the amplifier module. The amplifier module, housed in an aluminum case, is located near the distributor.

System uses 2 ignition coils. See Fig 1 . Main coil is connected in parallel with primary windings of auxiliary coil. The secondary circuit of auxiliary coil is not used and coil tower is sealed.

Fig 1: XJS Schematic Of Lucas Constant Energy Ignition

Courtesy of JAGUAR CARS, INC.

Reluctor turns with distributor shaft. As each of the 12 teeth pass across the pick-up coil's pole piece, the magnetic field strength around the pick-up winding is intensified. This creates a voltage in pick-up coil windings.

The rise and fall of this voltage is sensed by the amplifier module, which then sends a signal cutting off voltage to the primary circuit of ignition coil. This causes a voltage surge in the secondary, firing spark plugs.