The General Motors HEI (high-energy ignition), introduced in the early '70s, became the standard General Motors ignition system after 1974. Its simple one-wire hookup makes it a common retrofit to replace early points-type ignitions on vehicles. The HEI provides more than double the spark output at 40,000 volts compared to the 18,000 volts of the points-style ignition. Setting up an HEI distributor on a Chevrolet is a simple remove-and-replace procedure.
Turn the engine to top dead center on the compression stroke of the No. 1 cylinder. The easiest way to accomplish this is to remove all the spark plugs and turn the engine over by hand until you feel compression in the No. 1 cylinder. Then turn the engine until the timing marks on the crankshaft pulley line up with top dead center.
Remove the distributor cap from the distributor, and mark the direction the rotor is pointing on the firewall with a marker or paint pen. This will make lining up the new distributor easier.
Remove the old distributor by unplugging any electrical connectors and removing the distributor hold-down bolt at the base of the distributor. Then pull the old distributor out of the engine. Once you have removed the distributor, do not allow the engine crank pulley to be moved.
Position the rotor at the mark you made, and insert the distributor into the engine. You will notice that as the distributor drops into position, the rotor will turn slightly. If it does not line up with the mark you made on the firewall, pull it back up and rotate the rotor slightly to compensate for the rotation as it slips into place. It may take a few tries to get it into place. Then reinstall the hold-down and electrical connections.
Install the distributor cap, and plug wires in the same firing order as before. Start the engine, and allow it to warm up. If the engine doesn't start right away, rotate the distributor slightly until it starts.
Set the timing when the engine is warm.
