Good luck, I have two 71 B bodies and I've just about given up on trying to get the vacuum controls to work! I truly hope you get it working so I can pick your brain.

Actually, my advice is to troubleshoot it one link at a time. I'd install a manual valve where the heater control valve would normally go, and then see if everything else works properly. If everything else works, then install a vacuum controlled valve and experiment.

In my opinion, the 8-hose vacuum control is really interesting! It's essentially an 8-bit control unit using vacuum rather than electronics.

Jim