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Compressor Lubrication.  I did one final thing before installing the compressor in my Jeep--I checked the oil.  While cleaning the compressor, earlier, I had it sitting upside down for several minutes and noticed that a foamy, yellowish oil was leaking out of the manifolds.  So I removed the two manifolds and the head of the compressor to see what was inside.  It appears that there are two chambers within the compressor: the oil reservoir on the bottom half and the upper air chamber.  It didn't seem to me that there was supposed to be any oil in the upper chamber, so I turned the compressor upside down again (with the head still removed), and drained about two tablespoons of oil from the upper chamber.  Then I turned the compressor back upright, and reinstalled the head and the manifolds.  Next, I removed one of the oil fill plugs on the side of the compressor and drained another two tablespoons of oil out of the reservoir (since this compressor can be mounted either vertically, horizontal right, or  horizontal left, there are oil fill plugs on both sides of the compressor--you can use either one to drain or add oil). 

CAUTION: Regarding the mounting position--this compressor was manufactured as an air conditioner compressor.  For our conversion to an air compressor, it must be mounted in the vertical position only!  If you mount it horizontally, the oil will seep out of the reservoir, into the upper air chamber, and into your air supply.  You could use an in-line air-oil separator and/or filter, but that would totally defeat the whole purpose of using a York compressor in the first place.

Anyway, I'm glad that I checked the oil, because it seems that it was extremely low.  One of the web sites I used extensively throughout this project was that of Ben "Obi-Wan" Hollingsworth.  Specifically, his York Compressor for On-Board Air Page.  From there, I learned that the compressor oil capacity is 12 ounces (much more than what I had been able to drain from my compressor!).  I fashioned a dipstick, as described on Obi-Wan's site, and used my little 6-ounce, trigger-pump oil can to fill the compressor with fresh 10W-30 motor oil.  Since I knew how much my little oil can held, fine tuned with the dipstick that I made, I was confident that I now had the proper amount of oil in the compressor.  It's kind of hard to see, but the lower end of the dipstick has two little black marks on it.  The lower mark is at 1 inch and the upper at 1¼ inches.  With 12 ounces of oil, the dipstick read exactly between the two marks.

Compressor Installation.  The compressor is finally ready to install in my Jeep!  However, it wasn't quite as easy as I had expected.  Although the Kilby compressor brackets are very well engineered, it is nonetheless an extremely tight fit.  The four bolts that hold the compressor to the bracket are very difficult to get to with anything but an open-end wrench.  So I modified the installation procedures a little bit.  First of all, I removed the passenger side engine compartment support rod (attached with one bolt on each end of the rod).  Next, I removed the mounting bracket that I had previously installed and loosely attached the compressor to the bracket using the four bolts that came with the Kilby bracket kit.  Then I reinstalled the mounting bracket/compressor assembly to the engine and slipped the V-belt (which also came with the Kilby kit) over the new alternator pulley and the inside pulley on the compressor.  Using a crowbar and a block of wood as a lever, I raised the compressor upwards on the mounting bracket until the belt was tight (but not too tight--about ½-inch deflection while pressing on the center of the belt between the alternator and the compressor).  Finally, I tightened the four mounting bolts.  

The Kilby bracket kit installation instructions warn you that, depending how your rig is set up (e.g., body lift, engine lift, etc.), you may or may not have to either cut the fender well to clear the compressor or bend the engine compartment support rod above the compressor.  I have a M.O.R.E. one-inch body lift and Currie one-inch lifted motor mounts in my Jeep.  And although I did have to bend the engine compartment support rod slightly upwards and to the right (towards the center of the engine compartment), I did not have to cut or crush the fender well to clear the compressor.  Once installed, I immediately cranked up the engine to see if the compressor worked properly.  It got all tingly when I touched the clutch wire to my battery and felt the massive rush of air gushing out of the discharge manifold!  :-)  Here are a couple of shots of the completed compressor installation.  Notice how the passenger side engine compartment support rod is slightly bent in order to clear the discharge manifold.