Eli Gald the ground wire helped. Couple of things. I don't know which pulleys you have on your motor? They may slow down the fan and Alt. You didn't say what the amp rate was for the Alt? If you have Lights, Radio( size of amps), Fans ( how many) It is easy for your car to be pulling 50 amps drain at idle with al this on. What is your Ignition system? MSD or Accell Both pull alot of amps. Check the system with everything on at 1K rpm and get the volt reading. You may need to go to a 100 amp or 120amp alt to keep the system working properly. Do you have an electric fuel pump? Fuel injection? Give me a list of all the power systems in your car and we will fine you the correct Alt for it.
Rick Lake