If you determine that your voltage regulator is bad, I sell the electronic solid state voltage regulators eBay for $19.95 including shipping.
Mopar Voltage Regulator - Electronic Solid State with Correct Restoration Look
Does the headlamp switch feel hot or warm to the touch? Sometimes they will get hot when they are failing.
The stock alternator in your '66 Imperial is likely in the 35-45 amp range (in the higher range with A/C), which is not enough amperage to keep up with the draw that happens if you are stopped with the brake lights and headlights on. The easy fix may be to increase your idle speed slightly if everything checks out as being good.
Just my opinion - Anyone using more than a 50 amp alternator in their C Body with stock wiring should do an amp gauge bypass. Search the archives on moparts.com and read about this topic.
Mopar Voltage Regulator - Electronic Solid State with Correct Restoration Look
Does the headlamp switch feel hot or warm to the touch? Sometimes they will get hot when they are failing.
The stock alternator in your '66 Imperial is likely in the 35-45 amp range (in the higher range with A/C), which is not enough amperage to keep up with the draw that happens if you are stopped with the brake lights and headlights on. The easy fix may be to increase your idle speed slightly if everything checks out as being good.
Just my opinion - Anyone using more than a 50 amp alternator in their C Body with stock wiring should do an amp gauge bypass. Search the archives on moparts.com and read about this topic.