oil bath air filter

I've got a chance to sell my '72 super, all I have to do is drive it 1200 miles to Virginia. Leaving Sunday. But here's the thing: I had it built with a paper air filter, but I removed the paper filter assembly and put it on the engine in my recently restored '69.....all I have left is the oil bath air cleaner. It has the warm air riser, with a flap operated by the temperature in the air cleaner. Not by vacuum, but by what I think would be called a 'heat motor', or a 'wax motor'. It's a small brass cylinder with a plunger in it, that gets warm and expands the stuff inside, forcing the plunger out to open the flap, reducing the amount of warm air from the riser, and increasing the cold air from the snorkel. My question is, how is that supposed to be adjusted? The small brass cylinder is on a turnbolt to adjust the stroke. Must be a proper way to calibrate it. Anybody know?