volt meter

That "ping" may be a wire (battery wire from the alternator?) bouncing off the alternator fan (or pulley). You could also have a problem internal to the alt.

Do you have a one wire alt or a 3 wire alt (remote mounted regulator)?

If you have a remote mounted reg, that would be suspect also. Try unplugging the reg connector and see if that corrects the problem. If there is a wire near the reg that has an intermittent ground when the engine is running, and unplugging the reg stops the voltmeter pulsing, then unplugging the reg may appear to be the culprit (but isn't).

What does the voltmeter read with the key on (run position) and the engine not running?

John

Thanks for the reply.
The alt is a three wire, just as the one replaced. I think it is internally regulated. It is the Ford unit. The frequency of the pulse (it is a soft ping) does not change with engine speed.

I'm not at the car now but will check the static voltage asap. Normally the initial volts are 12.5-13 and charge indicates 14.5-15 but steady.