[petek]

This is one of those times that a voltmeter would be helpful. We'll assume from the brightness of the headlamps that the voltage climbed up pretty high. How high? Who knows! Obviously not high enough to blow out the headlamps or MSD box.

It *could* be the internal voltage regulator in the altenator ... but it could also be a bad ground to the engine (or maybe the battery). What I'm thinking is that a bad engine ground would make the voltage regulator in the altenator think that the voltage in the rest of the car (i.e. the battery) was too low. The v-reg would then bump up the voltage and attempt to bring the battery voltage back up.

I'd go through and make sure all of the connections (battery, altenator, starter, ground to the engine, any connection with a wire around 12 awg or less) were clean and tight.

Next on the list would be to see if you can get the problem going with the car in the garage. If you can get the problem to come back, take a voltmeter and measure the voltage between the engine and the chassis ground and then battery ground. You should not see any voltage, but if you've got a bad ground, you'll see some voltage.