Chevrolet HEI Distributor Casting Number Reference

General Motor’s HEI distributors are still going strong.

GM’s High energy ignition (HEI), designed and built by the Delco-Remy division of General Motors starting in 1974. These units were used on all engines in 1975 through the mid-1980s, with several different variations over the years. Characterized by the incorporation of the ignition coil built into the distributor cap which eliminated the need for a coil wire.

The system consists of a control module and a magnetic pickup inside the distributor housing which removed the ignition points and condenser. The control module basically performs the same function as the breaker points in a points and condenser system.

Within the General Motors supply system, the choice in HEI system type was important based on the engine that it was used in. Each GM division had its own engine design so a Chevrolet distributor would not fit on an Oldsmobile, Pontiac, Buick, or Cadillac engine or visa-versa.

 

While the distributors may look alike, the parts inside are not alike especially in terms of the ignition coils and the pickup coils. Ignition coils and pickup coils should be considered a matched set. Look at the color codes on each part and match the codes to each other, and to the vehicle/engine family the distributor will be used in. Failure to use the appropriate color codes may result in poor starting and misfiring at low speed.

Color codes must match from the pickups to the engine/vehicle.

The control module type is important as well. The control module is the heart of the HEI system. There were three basic types of HEI control modules. The four-pin control module unit, which was used on non-computer controlled, conventional carbureted engines, used mechanical timing controls (vacuum and centrifugal advance).

As the name implies, there were four-electrical terminals in the four-pin control module. Two-large terminals, one for battery voltage input and the other was the ignition coil grounding terminal. The two smaller terminals were for the pickup coil leads. These modules are the most common and are still favored by many oval track racers and street rodders on non-computer controlled engines. 

The five-pin control module was introduced in 1978 and the original version included a provision for connecting a knock sensor. This evolution was an attempt at electronic timing control. There are three different versions of the five-terminal control module. The three different types are not interchangeable. 

  • HEI/EMR  Electonic Module Retard used a wire connected to a switch or to an electronic control package.  Under certain conditions, the switch or control package will ground the wire, which triggers the retard feature built into the distributor module.
  • HEI/ESC  Electronic Spark Control used a knock sensor and an electronic controller.  The knock sensor sends a voltage signal to the controller, which sends a voltage signal to the distributor module, activating the retard feature within the module.
  • HEI/ESS  Electronic Spark Selection used an outboard electronic decoder which receives voltage signals from three sources:  a manifold pressure switch, the distributor pickup coil, and an engine temperature switch.  The decoder processes the information and provides a voltage signal to the distributor module to adjust the amount of advance/retard.

All the five-terminal control modules are used with distributors having conventional centrifugal and vacuum advance mechanisms.

Next was the seven-pin control module which was used on computer controlled engines. Because the computer controlled the ignition timing, there were no mechanical timing control mechanisms on the distributor. These distributors cannot be used on non-computerized engines. The seven-pin control modules are referred to as HEI/EST (Electronic Spark Timing) distributors. All timing advance was pre-programmed into the computer, using information from an array of engine sensors.  Base timing could be adjusted, however. 

Chevy distributors have casting numbers and casting dates, which can be useful if you are trying to find out the original application the distributor was used in. The housings are date coded and stamped with casting numbers of their respective engine or vehicle application. The numbers were either stamped into an aluminum ring that was wrapped around the upper part of the distributor shaft housing, had a stamped plate riveted to the housing or was stamped into the housing itself.

How the four-pin module works.

Casting #    Year            Notes

1103200     1976          350ci, Corvette L82, California models

1103203     1976          400ci, Chevelle, Monte Carlo

1103209     1976          262ci, Monza, California models

1103239     1977          305ci

1103244     1977          305ci, California Cars

1103246     1977          350ci, Corvette

1103248     1977          350ci, Corvette, California models

1103252     1977          305ci, high altitude Cars

1103256     1977          350ci, Corvette L-82

1103257     1977          350ci, Corvette L-82 California

1103258     1977          350ci, Corvette L-82 high altitude

1103281     1979          305ci

1103282     1979          305ci, California cars

1103284     1980          350ci, Z-28 Camaro

1103285     1978          350ci, Corvette California

1103286     1978          350ci, Camaro, Nova, high altitude

1103287     1980          350ci, Corvette L-48, Manual transmission

1103291     1978-79    350ci, Corvette L-82

1103337     1978-80   350ci, All

1103353     1978          350ci, All Standard, high altitude

1103368     1979-80   305ci, All

1103370     1979          267ci, Malibu, Monte Carlo, Auto transmission

1103371     1979          267ci, Malibu, Monte Carlo, Auto transmission

1103379     1979          305ci, All

1103382     1980          267ci, Malibu, Monte Carlo

1103383     1980          267ci, Impala

1103384     1980          305ci, All high altitude

1103386     1980          305ci, All California

1103387     1980          267ci, All Except California

1103425     1980          350ci, Corvette L-82

 

 

About the author

Bobby Kimbrough

Bobby grew up in the heart of Illinois, becoming an avid dirt track race fan which has developed into a life long passion. Taking a break from the Midwest dirt tracks to fight evil doers in the world, he completed a full 21 year career in the Marine Corps.
Read My Articles

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