Originally, the HEI system was fitted with a four-pin module. By 1978, it had a five-pin unit. Seven and eight-pin modules were more a computer-controlled element that came around in the 1980s.

Today, there are several aftermarket high- performance modules and coils that can be added to a stock GM HEI distributor to give it excellent spark energy and rpm potential up to 7,000 rpm.

Any four-pin '74-'90 GM HEI module will work in an emergency situation and is readily available at any auto parts store, just don't expect the performance of the Dyna-Mod. See All 15 Photos ...

Here's the drill. If you have an AMC, a Ford, or a Chrysler distributor with a magnetic pickup, it's really easy to convert to a standard four-pin GM HEI module.

If you're swapping points to an HEI distributor to lower maintenance requirements, you're good to go, but will you be able to feel a difference if you do?

When General Motors introduced the High Energy Ignition (HEI) distributor in the mid-1970s, it was revolutionary. So much so that it still has a strong following among today's hot rodders.

General Motors reportedly refused to replace a faulty ignition switch that would have cost the company less than one dollar per car, Reuters reports. The defective switch is believed to have been ...

GM recall came years after defect was discovered 03:52. General Motors said last week that it was recalling more than 700,000 vehicles because of a problem with the ignition switch.

DETROIT (AP) - General Motors is adding 218,000 subcompact cars to its growing list of recalled vehicles.