The spark timing that ignites the compressed petrol/air mixture in each cylinder is critical to performance. Detonation is more likely if it occurs too soon. It is distinguished by a tinkling noise. This means that the fuel in the cylinder is exploding suddenly rather than gradually. Timing marks are commonly found on the crankshaft pulley located at the front of the engine. In this case, the engine has a series of pointers that indicate various degrees of ignition advance.
A test lamp can be connected between the low-tension terminals of the distributors and earth to indicate when the distributor points open. If the distributors lack a fine adjuster or the ignition timing is off, a single clamp bolt or a number of fixing bolts or nuts must be loosened slightly to allow the distributor body to be turned.
There is a stroboscopic timing light in use. A tachometer (rev.counter) is recommended to ensure that the dynamic ignition timing meets the manufacturer’s specifications.