Voltage Regulator and low output from Alternator
Did you ground the second field terminal?
Basically this is a simple circuit
The regulator MUST be grounded. MUST!!!
The regulator has two connections, IGN and FIELD
IGN goes to switched 12V from the ignition switch, and this is subject to "suspected" voltage drop
FIELD goes to either field terminal of the newer style alternator
The remaining field terminal must be grounded.