Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Ignition System - HEI: Description
The Delco-Remy High Energy Ignition (HEI) system incorporates a distributor with integral electronic module. The complete system includes a battery, primary and secondary wiring, ignition coil, spark plugs and ignition switch.
The HEI distributor housing contains a magnetic pick-up coil, pole piece (with internal teeth), timer core (with external teeth), electronic module (with built-in radio noise suppression capacitor), rotor and distributor shaft. See Fig 1 . An electrical connector on the side of the distributor housing connects the HEI system with the vehicle's ignition and battery wiring.
The ignition switch terminal and ignition coil have full battery voltage when the ignition switch is in the "ON" or "START" positions. A ballast resistor or resistance wire is not used on the HEI ignition system. The ignition coil is attached to the engine block, next to the distributor.
All ignition timing changes in the HEI Electronic Spark Timing (EST) distributor are done electronically. The Electronic Control Module (ECM) monitors information from various engine sensors, computes the desired ignition timing and signals the distributor to change timing accordingly.
Vacuum or mechanical advance mechanisms are not used on HEI EST) distributors. Some Chevette and Pontiac 1000 models are equipped with the EST distributor. See ELECTRONIC SPARK TIMING (EST) IGNITION article in this section.
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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.
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