What Is an HEI Distributor?

by Contributor

HEI distributors were a type of ignition component made by General Motors. They remain popular as parts for older cars being rebuilt or restored--mostly muscle cars.


GM designed the original HEI system to overcome the less-potent fuel mixes available to drivers due to more stringent environmental regulation and the energy crisis. With traditional ignitions unable to make the most of leaner fuel, the HEI came about, hence its name: High Energy Ignition.


These HEI distributors were a stopgap between older ignitions and the computer controlled varieties of latter eras. HEI products were installed in GM vehicles during most of the 1970s and 1980s, when they were replaced with more advanced solutions.


The increased efficiency of HEI distributors stemmed from the incorporation of the ignition wire into the distributor cap, reducing degradation of the spark and loss of energy potential.


Pre-1975 HEI distributors tended to overheat and cutoff around 5000 RPM, making them less desirable in high performance uses. GM corrected this problem with later models, which were rated up to 7000 RPM.


One added bonus of the HEI system is the lack of a coil wire. Not only does this make the spark hotter and more potent, it also eliminates the need to adjust the ignition wires now and again. This happens even with more modern variations to this day.

Time Frame

Although superseded by newer technology, HEI distributors remain very popular among muscle car restorers working on cars from the 1960s, as well as among owners of older Jeep models. Companies such as MSD still manufacture HEI kits for the enthusiast market.

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