I have a 78 Ranchero with an older 351 . I rewired the entire vehicle. My problem is this. I lose volts while my lights are on, gradually. It will run 12 volts if the battery is fully charged for a little while. Voltage regulator has been changed and alt has been changed. Again it has been converted to points and condensor. I have a resistor wire between the voltage regulator and ignition switch. I have another resistor wire between ignition switch and coil. I thought maybe I had alt hooked up wrong but checked that. If I loop the field with the stator wires to the field on the regulator I get 17 volts but it decreases sharply if I step on the brake or turn on the lights. Any suggestions.
When idling sometimes it will hold 12 other times will decrease gradually to 8 or 9.
I finally hooked up the stator and field wire to the same lead on the voltage regulator and it overcharges until lights and brakes are applied then it decharges. It still will not begin to charge until it is revved up.
Crazy but true.