How To Drive A Motorcar
A Key To The Subtleties Of Motoring

HOW TO DRIVE A MOTORCAR reverse strain can be taken from small and medium- powered engines by a strong arm and wrist. The writer practised this for some time with a 75 min. bore engine, with the spark advanced so that the engine backfired every time when it was turned slowly. In the early stages the compression cocks were partially opened so as to minimize the danger attached to the experiment, and these were gradually closed until it was found that the full shock of a backfire could be taken comfortably by the arm so long as one had prac- tised the movement and was prepared for it. As previously pointed out in a clear manner, this principle is not advocated for general adoption, but on the contrary is merely mentioned for what it is worth to those who have various types of engines to start up in which the ignition point is an unknown quantity, and also to show that the cultivation of a stiffly-poised wrist and forearm is an advantage in any case. So far as the average motorist is concerned, all that he learns from these few notes on this principle is that it is better to have the wrist fairly stiffly poised instead of loosely tensioned. Variable Firing Point Many cars in these days, especially the smaller ones, are not fitted with a variable firing point, as in practice the higher speed of the magneto is found to be, ipso facto, of such value that the resultant fiercer spark compensates in its greater i-apidity of action in flame propagation for the lack of advance ; in other words, it so chancea that the higher speed of the magneto in itself constitutes an automatic advance spark. In the case, however, of cars fitted with an advance and retard lever, one should invariably make a practice of glancing at the lever before starting up the engine. It is. not sufficient, as many people do, to make a practice of bringing the lever back to the starting-up position when getting out of the ear, as this does not overcome the possibility of someone moving it after- wards. Consequently, therefore, always make a point of casting a glance at the position of the epark lever to see that it is approximately right.