How to Change a Chevy Pickup Coilby Don Bowman
Over the years, Chevrolet has gone from a single coil to a coil installed in the distributor cap to individual coil-on-plug designs. The method used to control the dwell time that charges the coil has changed, as well as the grounding or firing circuit. Some of the early-model coils were designed to operate at lower voltages to prevent overheating. They operated in the 6-volt range and required a ballast resister to drop the voltage. These early-model coils should always be checked for their operating voltage.
Remove the air cleaner to gain access to the coil. Disconnect the electrical wires by removing the two nuts holding the positive and negative wires to the top of the coil, using a wrench. Pull the secondary coil wire from the coil tower.
Remove the coil from the coil-mounting bracket, using the 1/4-inch-drive ratchet and a socket to pull out the bolts.
Install the replacement coil in the coil-mounting bracket and tighten the bracket bolts. Attach the red wire to the positive terminal and the black wire to the negative terminal. Tighten the nuts and install the secondary coil wire. Install the air cleaner.
HEI Coil in Distributor Cap
Remove the air cleaner. Mark the No. 1 wire location by placing a piece of tape on the terminal side of the distributor. Pull all the plug wires out of the distributor cap.
Disconnect the electrical connections from the distributor cap, located on the driver’s side of the cap. There are two connectors—one is the power wire, and the other is the connector from the module to the coil. Just pull them down and out.
Remove the distributor cap with the flat-head screwdriver. Remove the top cover on the distributor cap, which conceals the coil, using a 1/4-inch drive socket. Unscrew the four screws securing the coil to the cap, using the 1/4-inch socket.
Lift the coil with one hand; with your other hand, pull the wire terminals out of the cap. They must be removed simultaneously. Turn the cap over, and drop the spring and center contact for the rotor out of the cap.
Insert the new center contact, followed by the spring. Insert the coil and the electrical terminals. Screw in the four screws and tighten. Install the top cap over the coil.
Place the distributor cap back on the distributor and tighten the screws. Plug in the large connector to the terminals closest to the cap. Plug in the power wire. Be mindful to perform this in the order given.
Install the plug wires starting with the No. 1 wire in the hole marked earlier with tape. The firing order for a Chevy V-8 is 1-8-4-3-6-5-7-2, and the distributor rotates clockwise. The odd number cylinders are on the driver side, and the even number cylinders are on the passenger side. Install the wires in a clockwise pattern starting after the No. 1 wire.