High energy ignition
 | This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these messages)
|
High energy ignition, also known as H.E.I., is an electronic ignition system designed by the Delco-Remy Division of General Motors. It was used on all GM vehicles, at least in the North American market, from 1975 through the mid-1980s.[vague] The system is an electronic system that requires no scheduled maintenance, provides up to 35,000 volts to fire the spark plugs and increase spark plug life, especially when unleaded fuel is used. The HEI system has 40% more voltage output and 85% higher energy level than conventional breaker point systems to fire lean fuel mixtures even under adverse conditions.
There were many design variations over the years, and provisions for computer controls were added for some applications starting in the late 1970s. A predecessor system called "Unitized Ignition" was optional on 1972 and 1973 Pontiacs. [citation needed]
Most—but not all—HEI systems have the ignition coil mounted in the distributor cap. A control module and magnetic pickup are mounted in the distributor, in place of a conventional ignition system's breaker points and condenser.
Control modules
[edit]There are four basic types of HEI control modules: four-, five-, seven-, and eight-pin. The four-pin module was used on carbureted engines and uses conventional mechanical timing controls (vacuum and centrifugal advance mechanisms).[citation needed] The five-pin module was introduced in 1978 and was an early attempt at electronic timing control; it contains a provision for connecting a knock sensor.[citation needed] The seven- and eight-pin modules are used on early computer-controlled engines in conjunction with fixed-timing distributors, as the computer controls the ignition timing.
Upgrading
[edit]HEI distributors are a popular swap on older GM cars originally equipped with points and condenser type ignition systems.[citation needed] The HEI system produces a more powerful spark, which allows for a wider spark plug gap for surer ignition of a fuel/air mix that may not be optimal. The HEI setup has also become a popular swap into non-GM vehicles.
References
[edit]