Compressor plumbing

by Jessy
(Clackamas, OR)

Hello, I am having an issue finding information. I'm building a air compressor that will be gas powered and i'm having a heck of a time figuring out what I need to do to make it work. I have a speedaire 3z172 compressor and will probably end up running it with an old wisconsin out of the shed. The plumbing for when it kicks down has me scratching my head. I've worked on gas compressors before, but only on the engine side. I'm a diesel mechanic so know how truck air systems work. The unloader is triggered by the governor to keep it from actually building pressure. Will the unloader in this compressor do the same thing? I know i'll need a valve to kick the engine back into low speed also, this just has a lever with a hole for linkage and an air line fitting on it correct? Also, I looked at the specs for this compressor on the grainger site and i'm slightly confused. It gives a rating at both 3 and 5 horse. With 2 different pump rpms of 459 and 788. Why is this? Also gives different pulley shiv sizes. I appreciate any help and apoligize for such a long post.