Alternator - low output?
 

A few weeks ago a booster battery was wrongly connected to the battery on one of my 454's. It managed to sizzle and smoke a little at the battery and heat up the engine wiring harness in a few spots. Now the electric choke no longer works and my voltmeter reads 12 volts instead of 13.5-14 volts. I removed the alternator and took it to an automotive electric service shop. They bench tested it and said it was fine. this past weekend I opened up the entire engine wire harness and inspected it. I found no bad spots and all wires carry continuity. Using a digital multimeter, while the engine is running I have checked the voltage at the battery & the main alternator stud. The readings are essentially the same (12.2 volts). The red/purple (sensor) and the purple (exciter) wires that feed to the alternator read just over 12 volts each. The angle boot that slips on a frame stud extension of the alternator is delivering about 3.5 volts to the electric choke. The motor, a 1998 carbureted 454, starts and runs just fine but I am concerned at how far from home I can travel before the battery won't fire the ignition. Does anyone have any suggestions on how to cure this charging problem?

Low output is usually a bad diode. Did they do a ripple test or just output? Testing with a volymeter probably won't tell you much. You need to get the unit on a heavy load to really determine what's going on.