Distributor
An electrical routing switch in older ignition systems that distributes high-voltage spark to each spark plug in order.
A distributor is a mechanical routing device used in older ignition systems (pre-2000s) to distribute high-voltage electrical current from the ignition coil to the individual spark plugs in the correct firing order. It is driven directly by the engine's camshaft.
Inside the distributor is a spinning shaft topped by a **distributor rotor**. As the rotor turns, its metal tip passes closely by electrical contacts inside the **distributor cap**, each connected to a spark plug wire. When the ignition coil produces a high-voltage pulse, it travels down the center wire, jumps across the rotor, and is routed to the corresponding spark plug.
Older distributors also housed the contact breaker points (which triggered the ignition coil to fire) and mechanical/vacuum advance mechanisms to adjust timing based on engine speed and load. Modern vehicles have replaced the distributor with individual Coil-on-Plug (COP) systems managed electronically by the engine computer.
Common distributor maintenance includes replacing the distributor cap and rotor (which wear out and develop carbon tracking), spark plug wires, and adjusting the base ignition timing by rotating the distributor housing. Symptoms of distributor wear include engine misfires, rough idling, hard starting in damp weather, and stalling.