How to test carb power valve? Stromberg
 

I don't have a wideband O2 on the truck yet so I feel a little blind.
Is there a way to verify power valve working correctly?
Stromberg WW 2 bbl.
The power valve actuation rod does move freely and will stroke w/ compressed air. The actuation rod piston is so small it looks like rod would hang easily.
Truck runs perfect. I'm interested for mpg. I may experiment w/ smaller power valve later. In last pic you can see float is notched to provide a path for power valve actuation rod to kiss power valve.