I don't now what it is but i did that and it worked. For some strange reason i think that what i did has someohow stopped a restriction in the air-bleed whole. If anyone read any of my earlier posts about the problem the engine always ran rich below half throttle. The engine didn't perform and differently when i moved the airbleed whole. Now, i can hear an rpm change when i adjust the airbleed whole. In turms of if i am worping the engine because of what i am doing. I don't think so. I loossened all for mounting screws before inserting the washers and the screws passed threw easily on all for. My friend does this on his inverted engines without a problem.