Voltmeter reading? Accuracy? Options

[SKL1]

Trying to figure out how accurate the OEM voltmeter is in my '73 2.0. To make a long story shorter the engine in the car is a much modified 1.9 from my '71, with approx 120K miles on the alternator.

Voltmeter reads around 11V and drops to 10 if I turn on the headlights. Immediately goes back to 11 or just over that with the lights turned off.

Replaced the voltage regulator this AM and did a test drive with no change. Gauge never gets close or above 12V. Makes me afraid to drive it at night with the lights on and go very far.

Do I need to go through the hassle of rebuilding the alternator or trying the alternator from the original 2.0 engine that has about 70K miles on it?

Better way to get a more accurate reading of actual voltage?? I hate electrical issues!!!!

TIA.

[emerygt350]

It's really not the voltmeter, I checked mine against a nice multimeter and it shows pretty dead on to that. The problem is where it is tapped into the system. Unless you run a direct wire from the volt meter to the battery you really only have another method of knowing your brake light is working.

I put a relay inline using the original wiring of the volt meter to trigger it. I have fused wire running from the relay to the battery and to the relay -> volt meter. The volt meter is now key activated (using the original wiring) and it only tells me what the battery is seeing. I went from a situation you describe to a nice steady 13.8.

I also use a digital adjustable voltage regulator and highly recommend them. Cheap, sturdy, and fits the slot.