Okay, displaying my ignorance here - I've got what started as a stock '89 Ford 5.0 EFI motor that I've put in a 39 Chrysler. I put a Holley intake and carb and headers on it, plugged the emissions holes in the back of the heads with bolts, got it running. Now I am trying to figure out the PCV valve. Basically, do I need to vent the valve covers, and/or run a standard valve-cover-type PCV valve? Or will pulling a vacuum on the oil fill tube be enough? At the top of the oil fill tube there is a large nipple to the side for a PCV-sized hose - I can easily run a valve between there and the base of the carb and be done with it. But then I got to thinking about the sealed valve covers (no breathers) and the emissions hose that used to run between the back of the heads. With the rest of the emissions crap removed, will I get undesirable pressure or something in the valve cover area? Like I say, ignorance on display. But like my daddy always said, ignorance is curable, while stupidity lasts a lifetime .