THE IGNITION LEVER

Rotorua Morning Post, Volume 3, Issue 682, 7 November 1933, Page 2

THE IGNITION LEVER

On cars not fitted with automatic ignition control, many drivers, because they do not realise the effect of advancing and retdrding the ignition, fail to obtain the best results from their cars in respect of power and economy by making insufficient use Of the timing control— frequently called the "spark lever." The commonest fault is runndng with the lever too far retarded, probably owing to its having been observed that in this position there is no tendency for the engine to "pink" when it is pullintg! hard and slowly. That policy, however, encourages waste of fuel, ovetheating, iburning of the valves, and failure to secure results in power development. To take an extreme case, if an attempt be made to driVe at, say, 50 miles an hour, on .a level road, twith the ignition lever fully retarded, approximately one-sixth to a. quarter of the strok'e Of th'e piston is "wasted." in other words, the fuel mixture in the cylinder is not fully igriited — the "eXplosion" is not compltete — funtil the piston has travelled through a considerahle proportion of its movement on the power stroke. This implies, further, that the gases are still hurning when the exh'aust valve op'ens, so that the valve and its seatings are liahle to be overheated, and become pitted and due for regrinding after a very much smaller mileage than is normal. Th'e best plan is always to keep the ignition hs far' advanced as possible, short of giving rise to piiiking. True, it is not possible in practice always to' secure that deal, but it is one that should be the aim of the driver. 'Roughly speaking, it means that all speeds on top gear above 25-30 miles air hour the ignition lever should 'be fully advahced.