I have a 1928 Gulbransen #274376. It has a 3 Double acting bellos motor. I just recovered the bellos and now it's out of time.
It runs in a jerky motion. I need to know to set
the rotary valves. or timing.
Thanks for any help on this matter. The only
number I found that mite help is 147475 under the motor.
Don Edward

The valves should be adjusted so that just as the first valve has rotated to the position that it no longer connects the pneumatic with the main supply, the next valve is in position to begin letting the main supply of air into the next pneumatic. Also, Gulbrnsen motors can be tricky to recover. If it does not move freely without binding, it will also cause it to run rough.

What position should the crank be in when you set the valves, then where should the valve
lock in position [with set screw] be in. Hope this makes science.