alt. or reg.?

[beedees]

    The lights and ammeter needle flicker at idle on my '67 R/T.  New (rebuilt) 55 amp. alt, new reg.  I have seen some remarks as to whether the second feild wire should be grounded, but don't know for sure . Mech. type reg. and shows to be charging about 13.9 v. , kinda hard to to tell . Any ideas? 

[Nacho-RT74]

if you are using double field alt with mechanical regulator, yes, you need to ground one of brushes. Using a metallic washer instead the isolator washer on to brush screw is enough to ground the brush

But since you already have the later alt, double field what is the "expensive" part to make the upgrade I would go with newer electronic regulator. Just need to add one blue wire to feed one brush with positive from ignition switch ( same line that feeds your existant regulator and ballast ) and will use the green wire to feed this time negative from regulator instead positive of earliers models.

Double field alt are ground regulated different than earliers that are positive regulated

so:
-blue wire with female spade terminal to alt brush
-elect regulator
-plug to elect regulator

AND THAT'S ALL !!! ALREADY UPGRADED. Difference is noticeable as several board members can confirm