Correct Primary Patterns

Good Primary Pattern (Parade):

A good primary (parade) pattern should indicate even ignition voltage line height between 200-350 volts.

Good Primary Pattern (Superimposed):

Display of a single cylinder should reveal a sharp short downward line at the closing point of the primary circuit. A slight upward line (current limiting) may appear at engine speeds below 2000 RPM. A sharp upward line (ignition voltage line) must be shown when the primary circuit is opened by the ignition control unit.