Distributorless Ignition Modules

Hello all,and Happy New Year. I was wondering what each Marque used back in the 90s when manufacturers were phasing out ignition distributors? For example Ford have EDIS.

Prior to DIS, GM had used a trade name "HEI" (High Energy Ignition) since the 1974 model year. But GM applied no trademark name for their distributorless systems, dating back to 1984 when it was simply identified as "DIS" for the Buick 231 cubic inch engine (that one should be familiar in the U.K. since it was used by Rover until 2006). There have been a number of changes based upon engine architecture, but a trade name was not applied to the systems to my knowledge.

There was an "Opti-Spark" system used on the LT1 and LT4 V-8s in the 1990s, but that was actually a distributor system.

Prior to DIS, GM had used a trade name "HEI" (High Energy Ignition) since the 1974 model year. But GM applied no trademark name for their distributorless systems, dating back to 1984 when it was simply identified as "DIS" for the Buick 231 cubic inch engine (that one should be familiar in the U.K. since it was used by Rover until 2006). There have been a number of changes based upon engine architecture, but a trade name was not applied to the systems to my knowledge.

There was an "Opti-Spark" system used on the LT1 and LT4 V-8s in the 1990s, but that was actually a distributor system.

Which certainly muddies the waters...

So when I toss up the hood of any car, what clues me in as to whether that vehicle has a distributor or distributor-less ignition system?

Obviously if you see a distributor the question is partly answered. If you see plug wires going into a coil pack. Then it is a dis system.

Obviously if you see a distributor the question is partly answered. If you see plug wires going into a coil pack. Then it is a dis system.

What would my 1981 Buick Century have been. I did see something round with wires coming from it under the hood.

Unless you're 1981 Century had a diesel engine it would have had a distributor. It was likely GM's HEI distributor with the coil mounted in the top of the distributor cap.

-Rod

Unless you're 1981 Century had a diesel engine it would have had a distributor. It was likely GM's HEI distributor with the coil mounted in the top of the distributor cap.

-Rod

Thanks for sparking my memory! Yes, I did see HEI in the service manual I bought for that car when I owned it. For some reason I thought HEI and a distributor were two separate things.

I think GM just decided it could be called "high energy ignition" because they didn't have the added loss of a coil wire.


-Rod

Prior to DIS, GM had used a trade name "HEI" (High Energy Ignition) since the 1974 model year. But GM applied no trademark name for their distributorless systems, dating back to 1984 when it was simply identified as "DIS" for the Buick 231 cubic inch engine (that one should be familiar in the U.K. since it was used by Rover until 2006). There have been a number of changes based upon engine architecture, but a trade name was not applied to the systems to my knowledge.

There was an "Opti-Spark" system used on the LT1 and LT4 V-8s in the 1990s, but that was actually a distributor system.
Excellent answer 👍