Voltage Regulator Testing?

Best way is just test it on the car

1.....What makes you think it's not?

2....Start by getting car warm and battery "normal." You still have an ammeter? It should settle down to "0" after charging up, at a fast idle. Then still on fast idle, hook a meter up right to the battery posts. Should run no less than 13.5, and no more than 14.5. Optimum is 13.8-----14.2

3....If voltage is low in above test, might be alternator. Try unhooking VR, and jumpering the two wires previously hooked to the VR together. This will "full field" the alternator causing it to charge maximum

Start engine, watch ammeter and voltmeter. Slowly bring up RPM. Voltage and amperage should go up. Try to keep below 15V. Turn on headlights, heater, any heavy load. Bring up RPM to fast idle or a bit more. Voltage should climb back up, and you should be able to come up above 14. If not, you have alternator or WIRING troubles

4....If charging voltage of a normally hooked up system is HIGH there can be several causes

Most likely is voltage drop in the ignition harness, "the path" from the battery to the VR IGN terminal.

Also, could be voltage drop in ground circuit. VR MUST be grounded to "same as" battery negative.

Could be VR out of calibration

Rare, but a bad battery can cause this as well