alternator problem

[Giro]

hey all, ive been trying to fix my truck for the past week and im stuck. i got a 74 620 and basically the alternator seems to not be working. the problem began when my battery kept dying. i figured it might be the battery wouldnt hold charge anymore. so i replaced the battery, and then it still kept dying. i so took the alternator off, went and got it tested. they said it was bad, so i got a new one. i put that one in, and im still having the same problem. ive tried to trouble shoot it so isolate the problem, but no luck. i know that if the car is running and you disconnect the battery, the alternator should keep the car running. when i disonnect the battery, the car turns off, as if the alternator is not working. also ive been told if i disconnect the alternator, the juice in the battery should keep it alive for a while until it dies. well, i disconnected the alternator from the battery and dies right away, even thought my voltmeter read 13 volts. im going to take the alternator back and have it tested in the case the new alternator is bad, but if it is still good, does anyone have anything else that might be a problem? also, quick question on the wiring; there are 4 wires: the red one that goes directly to the battery, 2 on a harness that goes to the external regulator, and a black one, which im going to assume its the ground. maybe it is a wiring issue, does this wiring sound wrong?

[datzenmike]

Check that the regulator is securely (electrically) bolted down to the fender and that there is a good ground strap from the body sheet metal to the negative terminal on the battery or to the block (same thing).

 

I'll assume the other battery cables are OK as you are able to start it, but go over them anyway.

 

If this does not do anything have the regulator checked.

[reese]

$10 regulators on EBAY, I bought one for my 74 and the same problem disappeared:

Search Ebay for: VR-148