Charging Problems

[70Ghia]

Ok need some help here.
I have a charging issue here, it seems that my once working system has now gone over board.
I have the Valeo Alternator with exter-regulator, 911 fan set up.
The other day after tuning the carbs, the alt-light came on, so I brought up the RPMs to normal operation but the light didnt go out.
So I tested the output of the Alt...good....12.8V
Looked at the idiot light in the gauge...good.
As the car was running, took the Positive lad off that battery...measured the out put.....a wopping 18.9 volts and climbing???
Checked the battery (optimum red top)....17.6 volts????
Rechecked the Alternator again and this time....nothing, no out put.
Rechecked the battery output......18.5 and going up.
Took the alternator out and talked to the local porsche guy here and he told me its common for the external regulators to go bad and one way to tell is the voltage out put will be high and the light will stay on.
So I changed it......didnt change a thing, same thing all over again.
To me, that tells me that the old ext-reg is still good.
And that I have some serious issues here but I have no idea why all this started out of the blue.
Any and all thoughts would be great.

Chris