hey man sorry took a min to get back to you with the reply on the engine driven compressor. but here is a good link to get you sarted, if you have any more ? just get back at me bro.

http://blogs.minitruckinweb.com/6393460/bloody-knuckles/engine-driven-compressors-r12-and-r134a-rotary-and-piston-style/index.html