[bobbader]

Filing is a bad option here since the lower venturi is part of the upper casting. If you start filing by going "around" the venturi, you'll do more damage. Depending on how bad the warpage is, a double gasket may work. If not, you have to be very crafty in "bending" the warp back down. This is a delicate procedure, but it can yield success with lots of patience. I suggest you do a Fordbarn Search for more information on this subject as there are a couple of different ways to fix this problem and the explanations are long.