Gas, tires, oil.

After putting in a new clutch bearing, I needed to plumb an air line and regulator to the air conditioning compressor. First I turned it over by hand to determin which was inlet and which was outlet.

Then I cut the outlet tube off even and drilled it out to 7/16″.

Using lots of oil (aluminum likes to gall) I tapped it for 1/4″ npt (pipe threads).

At this point most people would use a pressure switch to engage/disengage the electric clutch to regulate the pressure, in fact I had a pressure switch just for this (I had picked it up at a yardsale). But I has something even better, the regulator off of a gasoline powered air compressor. Unlike electric compressors, the briggs and stratton powered ones that contractors use run all the time, they just have special pressure relief valve that keeps the tank from over pressuring. The white nylon line on the right hand side goes to that valve. The main inlet from the compressor is underneath (normally this goes to the tank).

It also has a over pressure valve in case the main one fails, you need this no matter what kind of air compressor you have, an over-pressurered air tank can let go like a bomb.
Next I wired up a toggle switch for the clutch. Even without a tank, and with the engine idling, it put out a lot of air.

Above is a rig I made to air up or down 2 tires at once. Its faster and keeps equal amounts of air side to side. To air down, I just attach the air chucks to the valve stems and open the valve. To air up, I just hook up the air hose to the compressor and open the valve. In either case the gauge doesn’t read correctly with air flowing, but its easy to close it and check every once and a while. In fact, I’ve found that its nice for even just one tire: it has a built in gauge and you don’t have to keep bending over. Unfortunately, I’ve found that it doesn’t fill both tires equally, and it takes a really long time to equalize on its own (one air chuck probably has better flow than the other). But I still hook it up to two tires at once, then I just check each one individually.