Chevrolet's High Energy Ignition (HEI) also know as a breaker-less ignition, was introduced in 1975 as a replacement for the older mechanical breaker-type distributors. Normal maintenance for an HEI distributor involves replacing the distributor cap and rotor periodically, but if you are experiencing significant ignition problems, you may have to rebuild the distributor.
Release the two retaining pins on the distributor cap by pressing downward on the heads with a Phillips screwdriver and turning 1/4 turn. Move the distributor cap off to the side with the spark plug wires still attached.
Separate the wiring connector from the distributor base.
Mark the position of the distributor in the intake manifold by drawing a line with chalk or paint from the base of the distributor to the intake manifold.
Mark the position of the rotor inside the distributor housing by drawing a line on the distributor cap mating surface inline with the contact point on the rotor.
Remove the vacuum line from the distributor.
Remove the distributor hold down bolt and clamp and pull the distributor straight up to remove it from the engine.
Remove the rotor by removing the two screws that secure it to the distributor.
Remove the two screws that secure the ignition module. Label and disengage the four electrical connections from the module. Remove the module from the distributor.
Use a small punch to carefully drive the roll pin out of the drive gear at the bottom of the distributor.
Remove the drive gear, shim and tanged washer from the bottom of the distributor shaft.
Make sure the end of the shaft is smooth before sliding it upward to remove it from the distributor.
Remove the washer from the upper end of the distributor housing.
Remove three screws and remove the pole piece, magnet and pickup coil.
Remove the two screws that secure the vacuum unit to the distributor housing and remove the unit.
Take out the lock ring, then remove the pickup coil and retainer.
Remove the screw that secures the capacitor and remove the capacitor.
Remove the wiring harness from the distributor housing.
Clean all components with a solvent moistened rag. Replace components that are worn or damaged.
Reinstall the vacuum unit and the two screws that secure it.
Place the felt washer in position on top of the distributor housing, then place the shim on top of it.
Place the pickup coil retainer in the housing. Position the arm of the vacuum advance mechanism over the actuating pin of the advance mechanism. Secure the mechanism with the lock ring.
Reinstall the pickup coil and pole piece. Install the three screws that retain it.
Reinstall the washer in the top of the housing. Slide the distributor shaft into position and rotate it to ensure equal clearance between the shaft and the pole piece.
Install the washer, shim and drive gear on the bottom of the distributor shaft. Align the drive gear with the distributor shaft and install a new roll pin.
Loosely install the capacitor.
Install the electrical connectors to the B and C terminals marked on the ignition module.
Coat the bottom of the ignition module with silicone grease and install it into the distributor housing. Install the two screws that secure it.
Connect the white wire on the pick up coil to the W terminal on the module. Connect the the green wire to the G terminal on the module.
Reinstall the advance weights, retainer and springs.
Install the rotor and the two screws that secure it.
Rotate the rotor 1/8 clockwise past the mark on the distributor housing made during removal.
Lower the distributor into the engine. Make sure the rotor contact point stays in alignment with the mark on the distributor housing.
Turn the distributor housing until the mark on the intake manifold lines up with the mark on the outside of the distributor housing.
Reinstall the distributor clamp and retaining bolt.
Reconnect the vacuum line to the distributor.
Reinstall the distributor cap.
