Not charging HEI upgraded:
With the car running I'm getting 12.43 on the battery and 12.32 on the back of the alternator.
That first pic is the regulator and it's wiring is really simple.
The blue wire on the regulator plug should have 12v when the ignition is on, and the other wire goes to your alternator field terminal.
The regulator just senses the system voltage with the blue wire, and adjusts the field wire voltage to whatever the regulator thinks the charge amount should be out of the alternator.
I'd start by cleaning where it mounts really well and plugging it in.
These regulators need a good ground to sense and vary the charge output.
If it still doesn't charge then one of us can help further and see what's up, and in this case pics of the back of the alternator would help if you don't know if it's a dual or single field alternator.
Clean and remount the regulator first and see what it does.
Oh, and that HEI conversion is a work of art isn't it?
