[RICK LAKE]

Eli The rating for the alt is stamped on most Alts under the part number or it saids 100A , 120a some reading. You are pulling alot of amps at idle, Fans 15-18 amps high speed each, MSD 20-28 amps, electric fuel pump can pull 10-15 amps, radio 10-20 amps, lights 10-15 amps. Your alt is around 50 amps at idle and with what I just gave you you are short. The battery is taking up the extra drain. Proper wiring is very important for the charging system too. Out put wire from the batt stud should be 10 gauge min with a fusable link in there. Your option is a bigger alt or a pulley change to speed up the alt. I would go with the bigger alt. Find out the charging rate and then look in Jegs or Summit for a bigger Alt with more charging. Better TOO MUCH than not enough. Rick Lake Ps 4 wheel drive mag has them for sale too with heavy duty regulators, tio diodes, and bridges. Give me A call in the PM and I can try to walk you through it. after 8:00pm 732-254-3536. Is your voltage regulator internal??