When connecting the high tension wire to the coil, extreme care must be taken to make certain that the wire goes all the way into the coil until it makes a good contact. (See view at left side of Fig. 920.)
If the high tension wire does not make a good contact in the coil, the high voltage may break down the insulation and crack through the bakelite neck of the coil. (See view at right side of Fig. 920.)
When this occurs it not only cuts down the voltage at the spark plug gaps but eventually ruins the coil.
Be sure to watch this point when connecting high tension wire to coil.