I have been working on this thing for about 2 years off and on between other projects and I finally got it done, painted and mounted. I had to rely on my many years of experience to set the rotary valves as there is no good description I could find on just where to set the opening and closing of the four valves. I took my best guess on what I thought should work and it ran pretty good right away. It is quite the engine to watch running with all the linkage and levers moving back and forth. I run it on the shop air and once you get it going it uses very little air pressure to keep running.