Just for clarification, we're talking about a timing cover mounted dipstick, right?
There should be a tube going from the top of the timing cover to the bottom. Right at the top of the tube, above the water port, I have drilled a 3/16" hole below the top of the timing cover. This relieves the pressure from the crankcase in the tube and helps control the passing of oil to the top of the tube. You can also vent the pressure from the timing cover into either the lifter valley or externally to a puke tank.
There's more than one way to make a Ford almost as good as a Chevy.
DOH!
