I had
oil being sucked up through the PCV after a rebuild on my 289. The builder had modified the original baffle in the aluminum Cobra valve covers. I completely eliminated the
oil consumption by making a baffle with more surface area,keeping it close to the top of the cover,and and using thicker gaskets to give more rocker clearance. The goal is to reduce the atomization of the
oil by reducing the air velocity past the plate. That is why the baffle should be bigger. Also if oil is being sprayed up toward the PCV inlet the larger baffle will direct it away. Almost any light gauge sheet metal will work.