wiring a voltage regulator

Pompis that wiring diagram you posted is WRONG. Look at the one 73A posted earlier above. Notice that the IGN terminal of the regulator is hooked to the end of the ballast that is jumpered together, NOT the coil end.

Incidently, if you have a 4 terminal ballast, pay attention to the drawing RE: the "U" shaped cutout in the ceramic base, which properly orients the two sections of the resistor assembly.

In the diagram posted earlier, that "upside down U" is at the bottom of the ballast.

If your review some of my posts regarding voltage drop, the two biggest causes of overcharging is voltage drop in the regulator IGN terminal circuit, IE giving the regulator LOW voltage, as well as a poor ground between the battery and the regulator case