Originally Posted by Jaketab

Someone else may be able to explain better, but I'll try. One the Moki 5 cylinder radial engine there are 4 cam lobes. The cam ring or gear has 2 cams for the intake valves and 2 for the exhaust valves. The cams for intake and exhaust are 180 degrees apart. It takes 4 revolutions of the prop to make the cam ring turn 360 degrees. When you adjust cylinder #1 and the valves clearance is perfect. Then rotate the prop 2 times to the same position and the clearance may be slightly different. The cam rockers will be resting on the cam ring 180 degrees from the first valve adjustment. The clearance difference is due to tolerance on the cam ring that may be slightly different. Just make certain that the tightest valve gap is not too close. A slight difference will not hurt long as the difference is not too great or too close.