My voltage regulator was acting funny (it was the original, 40 years old), so I replaced it with a new one. The new one has the needle on my volt meter vibrating around 14 volts and the lights on the dash flicker when the car is idling (that stops when the engine is raced). I could not reuse the original rubber incapsulated nuts and bolts that secure the regulator to the radiator core support so I insulated it with rubber faucet washers. Any suggestions? Thanks.

There is indeed some weak point in the wiring, since the voltage levels when the engine is at a higher RPM. Obviously its smart to look right at those new connections to the regulator.

14 volt reading is just fine, but it should be constant and strong once at operating temp.

Did you replace the ground wire that runs from the regulator case over to the core support nearby? That is a ground return for the regulator. Without that wire, the regulator case will electrically float. It's a short wire, three to five inches long with a 1/4" or so ring lug at the core support end and connection to the regulator case ground at the other.

You can still buy the correct rubber isolator nuts. I bought some from a Corvette specialty vendor at one of the car shows. They are very common for GM cars of that era. This is not causing your problem, but you can put it back correctly if you wanted. Faucet wasthers won't provide the mechanical isolation that the original part gives.

Yes, I did replace the ground wire. I will check the connections again tomorrow and let you know what happens. Thanks for your help!

The output from a "modern" voltage regulator is controlled electronically. The old mechanical regulators had physical contacts. Some flicker is expected at low engine speeds, new cars do it too. But if the flicker is too pronounced, your alternator may be having internal issues. You can have the alternator tested for free at your local chain auto parts store.

How noticeable is the flicker, and how big a range of flutter at idle? What is your idle speed, and if you switch on the headlights and blower motor and A/C at idle, does it make a difference?

The flicker is slightly noticible; the LED on the radio (aftermarket) varies in intensity, as do the turn signals. The turn signal is steady as far as the blinking action, but the bulb output varies. This is only at idle. I will try it with the lights and blower motor on. Thanks!

Turning on heavy loads should force the alternator to output mode. This should increase the system voltage (and lamp intensity). What is your power-off battery voltage?

Your regulator may be switching at a relatively low frequency. Everyone has a different tolerance to refresh rates on a computer screen, some people (me included) are irritated by the 60 Hz refresh on a computer screen or from fluorescent fixtures. I need to run 80 Hz or better on my screens to avoid the flicker effect.

Battery off power voltage is 12 volts. The flicker goes away when the headlights and blower motor are on. I guess I'll just live with it as the car starts and runs fine otherwise. Thanks.