Pardon me for gumming up the forum with another electrics thread (and I thought the Lucas positive-ground electrics in my old MGB were a nightmare!) but I'm having an issue with the headlights load in my '66 Charger (with '70 Cuda 440 RB transplant). Transplant mill is decidedly cold-blooded already, but when I turn on the headlights the engine idle goes from rather rough to undriveable and will sometimes stall completely. Would the extra draw from the headlights circuit alone be that much more of a load on the alternator so as to cause a significantly increased torque pull on the engine? Seems awfully unlikely.

Granted, with the fairly aggressive Comp Cams cam, Eddy Performer 440 intake, Holly 750 carb combo feeding stock heads I'm having problems trimming for a stable warm idle as it is. Some slight degree of oil fouling of the plugs likely isn't helping either. Still, I would not think the extra load from the headlights could make that much of a difference.

 

Sounds like more of a voltage drop issue..