A timing light or timing gun is a device that allows you to see the exact moment a spark is firing. It works by flashing a beam of light for every spark, allowing you to set the timing of your engine for maximum performance.
By placing an inductive pick up on the HT lead, the timing light can detect the spark energy and produce a brief, intense flash of light at the exact moment the spark plug fires. When you point the timing light at the timing marks on the crank pulley of a running engine, the bright flashes of light have the effect of freezing the position of the timing marks on the pulley, thereby showing the exact ignition timing of the engine.
By watching the timing marks as you rotate the distributor body, you can set the ignition timing very accurately. Prior to the arrival of electronic timing lights, ignition timing would be set statically, i.e. with the engine switched off. This method involves a fair amount of trial and error, and is not as accurate as dynamic timing with a timing gun. As cars moved from points to electronic ignition, and then on to distriburless crank fired ECU systems, the use of timing lights in vehicle workshops has declined! At Powerspark we offer a range of timing lights, from a basic no-frills design to a more complex gun with a digital readout.
Powerspark Ignition - BLOG 