The use of wide sparking plug gaps has been shown to effect an improvement in both performance and economy, especially if most of the car’s running is done with comparatively small throttle openings. This is because the wide plug gaps enable a lower and more even idling speed to be used. The use of such gaps imposes a greater strain on the ignition system which the Sports Coil will compensate, being specially designed to withstand higher voltages.

It must be realised that, with small throttle openings, the gas is not a homogeneous mixture in all cylinders, but contains a considerable proportion of burnt gases. The greater volume of spark from the wider plug gap results in the increased probability of an ignitable portion of the gas being in the path of the spark and so giving more uniform firing at low speeds. Most ignition distributors incorporate a centrifugal automatic timing control built into the body, and these are designed to enable the engine to give maximum power at full throttle, whereas with a smaller throttle opening some extra advance is desirable in order to give maximum power at that particular throttle opening. With wide plug gaps, the amount of extra advance needed is reduced by several degrees and consequently the existing ignition timing (without alteration) is more nearly correct, again resulting in a slight increase in economy. Do not forget that, in order to obtain the best results, the carburetter should be adjusted to give a weaker mixture.

No doubt you will desire to have a high voltage sports coil, and you cannot do better than to fit the one marketed by Lucas. It retails at 21/-, is finished in polychromatic brown, and has the advantage of being easily obtainable from any Lucas agent.