Hello,This is a stock 1980s 305 SBC engine, suddenly I started having this problem with my battery voltage gauge where it would be at 14 volts when I first start the engine and then it would start to drop to about 12v and below while still idling and with no load. I checked the alternator belt tension, tested the voltage to the battery with the engine off and I was getting about 12+v, then I tested the battery with the engine running and nothing else turned on and the voltage was about 11.5v. The fact that the battery voltage was lower with the engine running led me to believe that the problem was the alternator not charging. So I recharged the battery overnight and bought a brand new 100 amp alternator and now when I started the engine the battery gauge was only showing 11 volts. The engine did cranked right up but it appeared that the alternator was not doing anything and revving the engine made no difference. Battery has new posts and secured connections. Could someone please help? Thanks in advance for your inputs!