[jw71elcamino]

This is what I found. Looks like the singe side goes to the manifold, The T side goes to the VA Pot. Not really sure where the other part of the T goes to for clean air vent. Maybe present on your carb or the air cleaner?

View attachment 833599

Heres the link

Timing Control Switches (TCS) Explained | Ground Up Motors - SS396.com

TCS or Timing Control Switches are a device found on early 1970's early GM vehicles. At first glance you might think TCS means Traction Control System, but

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Yes, it goes to the air cleaner.

 

[jw71elcamino]

Thank you, 70ECCustom and jw71elcamino! Great information. Would you happen to know where on the air cleaner the hose would go? It’s a stock cleaner and the only lines to it are to the thermal intake vacuum sensor—a vacuum line in from the rear of the 2 bbl Rochester, and one out to the ThermAC on the snorkel.

My '71 is different but your '72 may have not connected to the air cleaner for a "fresh air" source, but from the factory, had a rectangular/square piece of gray foam over that port as a "filter". They disintegrated over time and appeared as if they were disconnected. Again, that port is for a "clean/fresh air" vent source, not vacuum.

Note: The following image is from the factory GM '72 TCS manual. Other manuals may incorrectly show the "filter" port connected to a vacuum source.