Practical Hand Book of Gas, Oil and Steam Engines / Stationary, Marine, Traction; Gas Burners, Oil Burners, Etc.; Farm, Traction, Automobile, Locomotive; A simple, practical and comprehensive book on the construction, operation and repair of all kinds of engines. Dealing with the various parts in detail and the various types of engines and also the use of different kinds of fuel.

by John B. Rathbun

While the ignition should be considerably advanced while running, it is necessary to retard it when starting, as the engine is liable to “kick back” with an advanced spark.

This advance and retard device should be accessible while the engine is running, and the operator should be able to control the point of ignition at all times. Many men have been seriously injured by the lack of this device or by neglecting to use it.

The contact points make contact only for a short time before the spark is required in order to reduce the amount of current to the minimum, and therefore increase the life of the batteries.

The duration of the “make” or contact should be as short as possible. Prolonged contact weakens the batteries and causes them to run down rapidly. For the same reason the electrodes should remain separated until the make is actually required.

A certain period of contact is necessary, however, to allow the spark coil to “build up,” but with a properly designed coil the time required is very short.

Some engines provide a device that cuts out the ignition current altogether during the idle strokes. This adds materially to the life of the batteries.

The igniter should be located near the inlet valve, as the cold incoming gases tend to keep it cool and clean, besides insuring the presence of combustible gas around the igniter electrodes. Improper placing of the igniter will greatly reduce the efficiency of the engine. Avoid placing the igniter in a pocket, or in the path of the exhaust gases.

The make and break ignition system has many good features, but cannot successfully be applied to engines running over 500 revolutions per minute, nor can it be applied to engines of less than 3 H. P. as the parts would be too small and delicate to be durable.

The make and break igniter produces the largest and “hottest” spark of any type of ignition, and is especially desirable for large or slow running engines. Being operated at a low voltage, it is not as easily affected by moisture, poor insulation, or dirt as the high tension or jump spark system, nor is it liable to give the operator such a violent “shock.”

Engines governing by the “hit and miss” system have a device that cuts out the current during the “missed” power strokes. This effects a considerable saving in battery current, especially on light loads when the engine misses a great number of strokes.