Points and Condenser classic car ignition… What is it and how does it work?

How does a points and condenser ignition system work, and what are the pitfalls?

The points are a mechanical switch which are opened and closed by a cam on the distributor shaft.

When closed, the circuit is complete and the coil becomes energised. When the points open, the circuit breaks causing the energy to be released from the coil, creating the spark. The condenser reduces arcing across the contact points, helping the points to last longer.

At a cruising speed of 2,500 rpm, with a four cylinder engine, the points will be opening and closing more than 83 times per second, or 5,000 times per minute. That could be 30 million sparks in 6,000 miles. Although they are made from a tungsten alloy, it’s no wonder that the points need maintenance. At regular intervals the the maximum gap of the open points needs to be measured and adjusted if necessary. If the gap between the points becomes too small, the coil will be energised for too long and will overheat. If the gap is too large, the coil will not be fully energised between each cycle resulting in a weak spark. Eventually pitting on the contacts themselves and wear on the rubbing block mean that the contact breaker set will need replacing, usually after about 6,000 miles.