In the process of installing an Aviaid 6qt
oil pan on my 351W to replace the 9qt.
oil pan that came with the Ford racing motor. I have two gaskets shown side by side, one of which (Milodon) that has a notch on the driver's side towards the rear of the motor and the other (Fel Pro) that doesn't. Looking at the block, there appears what I believe is some sort of return passage that aligns with the notch in the gasket. Whats more, I also notice that on the 9 qt pan, there is a slight 'bulge' on the side of the pan near the rail whereas on the Aviaid pan, there is no bulge.
What exactly is this passage in the block? Is it a problem that the Aviaid pan doesn't have this small 'bulge'?