Technical Ported Temperature Vacuum Switch, Yay or Nay?

I’m trying to undo some home brew engineering on my truck that the PO had done. I’m looking at the vacuum lines around my carb and distributor and noticed that the Ported Temperature Vacuum Switch is not part of the system and indeed not even there. It doesn’t run bad, but I’m only getting 10 mpg. I’m looking at the vacuum diagram and it even has a check valve going to the vacuum diaphragm on the distributor. It’s my understanding that the switch is good for advancing the spark to prevent overheating, but I have no idea what the check valve is for. Do I need either one to make a difference in performance or mileage? The engine is a 302.




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Its a smog deal,just take a piece of hose and run from the carb to the vac. advance.

 

What Mr Griffin said

 

I used to replace them with earlier units that simply hooked to the carb; like mid to late 60's stuff. It worked fine, and I never missed the other arrangement.