So check this out. I just got done building my 325 stroker and I have the ford racing tall valev covers on it right now. I hooked up the tube from the throttle body and have it going into the valve cover via a grommet. When my car is running and I pull the dipstick out it creats a huge vacuum type suction sound, very very loud! That is scarey I think I need to vent the crankcase So I am goung to try and plug the tube now and run a breather and see if this changes things.