J57ltr 
So I have set my idle a little lower than normal to keep the car from pulling in gear in traffic and have noticed that the alternator cannot keep up at this low of an RPM the voltage would start out at 14.6 and slowly fall into the 12.1 range then kick back up to about 13V for a second then back down and wouldn't increase unless the engine speed increased, the fans would also speed up and slow down with this as well. I ended up buying a new smaller alternator pulley that measures 1.9" across the top of the ribs (Stock is 2.43"). This is nice and all, but the pulleys all have the offset about 7/16" away from the pulley and would pull the belt out of alignment. Not only that but the shaft is is so short that the new pulley doesn't even have any exposed threads. I ended up turning it on a lathe and got it down to where it fit perfectly and now even with the AC full blast and the lights on the voltage is able to hold and my fan no longer rises and falls with the idle. I may buy a few extra's and machine them if there is any interest or need.
Jeff
