NOTE: Some Chevrolet and GMC light truck models with 5.0L 4-Bbl. (VIN LE9) engines are equipped with Electronic Spark Control to combat detonation. ESC models have 5-terminal electronic modules in the distributor, while non-ESC models have 4-terminal modules.

The Delco-Remy High Energy Ignition system consists of a battery, ignition switch, ignition coil, spark plugs, primary and secondary wiring, and a special distributor assembly.

The distributor housing and cap contain vacuum and centrifugal advance mechanisms, an electronic control module, pick-up coil, pole piece (with internal teeth), timer core (with external teeth), rotor, distributor shaft and a capacitor for radio noise suppression. Some distributor models also include an integral ignition coil.

Full battery voltage is present at the battery terminal of the distributor in either the "START" or "RUN" position, as no ballast resistance wire is used.

Fig 1: Exploded View of HEI Distributor Timer core and pick-up coil pole piece have one tooth per cylinder.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Ignition System - HEI: Description

Use the Manual With the Right Hardware

When to See a Mechanic