The degree of advancement is also of importance. In the case of fixed ignition, which is now very rare, the question does not arise, for in this case the advancement is always sufficient. The majority of cars are nowadays either provided with automatic or variable advancement.
In the case of simple automatic advancement, it is best to set this in such a way that the ignition fires 1mm or 40/1000ths of an inch before top dead centre when in the starting position. In the case of variable advancement, the best average position in which to place the spark lever is half advanced.
BATTERY
If this is insufficiently charged, the speed of the motor will be too low and starting will be either difficult or impossible. The rate of engine rotation must
not be less than 100 to 120 rpm. It is almost unnecessary, therefore, to remind that for easy starting the battery must be in good condition and fully
charged.
In order to obtain the highest speed from the starter, it is good practice, especially during the winter, to loosen thick oil by a few turns of the handle before using the starter itself. It is also well to use slightly thinner oil during the winter. If all the above conditions are carried out, the engine should start without any trouble, but it is very important that the driver attends particularly to the detailed methods as set out on Page 10.