[BrianArmand]

1972 Cutlass 350 HEI. after a while, when the car gets hot (195+), and I have the headlights on (and step on the brake, which usually starts the bad behavior) the car at idle will start "surging". a voltmeter on the system indicates that the voltage is dropping from the 14.2 volt neighborhood to 13.5 or less. the engine sounds like it wants to stall, but catches and goes back to idle. this cycle can be like 2-3 seconds from near stall to back to normal. sitting there, the car can do this for minutes at a time (I've never let it go forever, but may try it some day...). if the car's hot and it's daylight, I have no issues. turn on the headlights and here comes the surging.

when the car is cold, the voltage is around 14.5, and when the car is warm it sits at 14.25.

it SEEMS like this first happened after I replaced the coil, cap and rotor. don't know how replacing any of those would have an effect on the car's voltage.

I've replaced the alternator and the external voltage regulator (and rebuilt the carb). Ive checked all the ground wires.

any ideas out there? thanks.
Brian