Ok so I have a '86 IROC with a 350 TPI. For about the last year the battery completely drains if I park the car for more than a day, sometimes shorter.
I started looking for the battery drain last week and it appears that the alternator is where it's coming from. If I disconnect the alternator field/regulator wires (the ones that plug into the alternator) the voltage drain goes from 12V and 12.50 amps to about 4V and 4 amps.
I can't seem to find anything that says whether or not the alternator should drain voltage from the battery or not when the car is off.

I have also checked all the other circuits in the fuse box and they seem to be fine.

Any help or thoughts are much appreciated.

 

A alternator should never drain power when not in use, It's goal is to produce power when in use. Sounds like it's internally shorted and needs replaced.

Anytime I found a battery drain issue (retired from the auto biz), First thing I did is removed the alternator battery wire to see if it was the cause......

 

Since an alternator is a three phase AC device, they have a sets of 3 diodes internally. One for each phase. Diode tend to fail shorted not open. Diode are electronic one way devices that let the current flow out of the alternator but not in. If one of the diodes is defective, it will drain the battery as it will not prevent the flow of current through the alternator to ground.
The output of the alternator is controlled by the current in the field winding. This current is controlled by the regulator. If the regulator becomes defective , it also can cause the alternator to drain the battery.
I am not sure what voltage you are talking about that goes to 4V and 4 amps with the alternator disconnected. I trust you are not running the engine with the alternator disconnected. That is a very quick way to fry the diodes.

 

No the engine is not running. I must have another drain on the battery that is causing the 4V 4 amp drain.
Thanks for the help, I figured it was a bad alternator.

 

So yeah, it was a bad alternator.