ignition: The Ignition Coil and Distributor

The primary winding consists of wire coiled around an iron core. Over this is a secondary winding of many more turns of finer wire attached to the distributor. Current flowing through the primary winding creates a magnetic field. When the breaker cam opens the breaker points or the reluctor delivers its signal, the circuit is broken and current stops. The magnetic field collapses, inducing in the secondary winding a much higher voltage that is led to the distributor. Inside the distributor a moving finger rotates at half engine speed. As it rotates it touches contacts, each of which runs to a different cylinder. Rotation is timed so that when the finger is touching the contact for a particular cylinder, a high voltage has just been induced in the secondary winding of the ignition coil and the piston has almost reached the top of the compression stroke. Thus a high voltage is impressed across the spark plug gap.

Sections in this article:

• Introduction
• Magneto and Diesel Ignition Systems
• The Spark Plug
• The Ignition Coil and Distributor
• Interrupting the Current
• Battery Ignition Systems

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