I have always had this problem with the car. It drives around on 14.0 volts then under a wot run its at about 12.5 @6500rpm. This is one of the reasons my injectors are getting hit so hard. My alternator is a 200amp so that cant be an issue. I have an adjustable regulator on it, sent it in for testing no problems there. I re-wired all my main power wires with 1 gauge, so nothing is too small...Any ideas this seems to be a common problem with the LT1 cars. Anyone that can data log around here sees the same results as I, with LT1's. Even a few that can see the gauge drop under wot.

 

I have logged my '95 Z28 using Diacom and it drops from 13.3V to 12.5V under WOT consistently. My charging system is stock and I have a Crane ignition and coil.

 

Did you ever get this fixed? mine is doing the same thing