I just found one of these still running. It has a slight knock but it still builds air PDQ. I have only found a small amount of information on these compressors on the mighty internet. I figured that if anyone knows about these old compressors, it would be hammers!!
Wouldn't hurt to pose the same question over on the garagejournal.com forum. I don't remember seeing anything over there but then again I wasn't looking for information on those in particular. Hard to beat the old iron! Ed
The Jalopy Journal
