How Does Opti-Spark Work?

A General Motors Opti-Spark is an optically triggered ignition distributor device.

A distributor refers to a device in an internal combustion engine's ignition system that directs voltage from the ignition coil to the spark plugs in the proper firing order. The Opti-Spark is a kind of ignition distributor used in certain engine designs.

Definition

Opti-Spark, designed by General Motors, is an optically activated ignition distributor device used on GM L99, LT4 and LT1 engines. The Opti-Spark is typically mounted at the front of the engine behind, or beneath, the water pump.

Function

Opti-Sparks consist of a high-voltage cap and rotor section and a low-voltage optical section. The optical section contains a disk with 360-degree slots, representative of 360 degrees of rotation from the crank. An eye unit called a laser directs a beam at the disk and reads pulses that are produced as slots pass through the beam. These pulses are timed by the cap and motor section, and are used to direct the timing of both the fuel injectors and sparks.

Issues

Opti-Sparks are often exposed to moisture sources due to their location. Car washes that include a carriage wash can soak the Opti-Spark, while driving through high water conditions can cause the Opti-Spark to submerge completely. Moisture buildup on the Opti-Spark can cause internal components to rust and fail.

References

• Delteq: LT1 Opti-Direct Ignition Systems
• "How to Rebuild Small-Block Chevy Lt1/Lt4 Engines"; Mike Mavrigian; 2002

Resources

• Corvette Fever: Opti-Spark Options