Spark Control System: Description

The Spark Delay Timing Control System is used to reduce HC and NOx emissions by delaying vacuum to distributor advance unit during acceleration.

This system consists of delay valve which reduces vacuum advance during acceleration mode. Calif. models are also equipped with a water thermo valve which prevents advance until engine coolant temperature is above 122°F (50°C).

Fig 1: Spark Delay Timing Control System Arrow on spark delay valve points toward distributor advance unit.