I didn't have a PCV originally with the 83-85 Stang valve covers, the baffles didn't survive the roller rocker clearancing, hence running a PCV valve with no baffle is a sure fire way to foul the spark plugs and drink quarts of oil in the process. I've since swapped covers to Moroso tall chrome steel (plain ones---no logo on these

) that have baffles. With the Stang covers, I had one open breather cap, the other had a 1/2 nipple that I routed a hose to the aircleaner, kinda hoped that would have been sufficient to vent the crank case. DIdn't happen though, I guess the 331's got a bit too much blow by at WOT for that to handle.I really wanted to keep the Stang covers as they pretty much matched the 3x2 air cleaner top. Maybe some day I'll get some baffles rigged in em.