How Large Can the Gaps Be?

A SET of curves has been developed that makes it possible to determine the maximum permissible spark-plug gap that can be fired by voltages transmitted through this critical region, the spark-plug barrel.

The investigation that led to the development of these curves consisted of the following steps:

1. 1.
   To determine a satisfactory way to simulate engine operating conditions in trie laboratory, this to consist of a correlation of spark-plug bomb pressures to various conditions of engine power.
2. 2.
   To determine the sparking voltages required to fire various gaps at the different bomb pressures corresponding to various engine power configurations.
3. 3.
   To determine experimentally the breakdown voltage for various spark-plug barrel configurations at different altitudes and to express this relationship analytically.