Which older car component controls the timing of the spark-plug discharges?

The component that controls the timing of the spark-plug discharges in older vehicles is the distributor. The distributor plays a crucial role in the ignition system by directing high-voltage current from the ignition coil to the appropriate spark plug at the precise moment, which is essential for the engine to run smoothly. It does so by rotating and aligning with each spark plug wire in a sequence that corresponds with the engine's firing order.

This timing is vital; if the spark plugs fire at the wrong time, it can lead to poor engine performance, increased emissions, or even engine damage. In older cars, which rely on mechanical components for this timing rather than modern electronic systems, the distributor was a key element in ensuring that the engine operates efficiently.

The ignition coil is responsible for generating the high voltage needed to create a spark, but it does not manage the timing of that spark. The voltage regulator is involved in managing electrical output to the vehicle's electrical systems, and a relay is an electrically operated switch, neither of which are responsible for timing spark discharges. Therefore, the distributor is the correct answer, emphasizing its critical role in ignition timing within older automotive systems.