[john hall]

Some guys run a small rubber line (maybe 2 cycle fuel line or something similar--as big as you can) through the funnel into the rear maybe a couple inches deep--helps if it was coiled up so it will try to curl up and out of the way of the stream of oil. This does a good job of letting air out. Also seen a pipe union (can't think of the correct term) welded to the rear cover plate kind of high up. This is the kind of "improvement" folks do when they have the back cover off for work or to completely clean out the inside of the rear housing.