My 63 is a 99% street car and I just ran these vented breathers as the hose just runs to the back of the eng in case they would spit a little oil it would not go on the valve covers. But it does not vent any oil out of the valve cover breathers as I dont have much blowby. And since my car is mostly a street car I went back to a PCV system for the street. It pulls enough vacum to work the PCV valve. And when I go racing I hook both breathers back up since the PCV dont vent the crankcase much at wide open throttle. The PCV system works nice on a street car pulling any excess crankcase vapors out and burning them in the eng combustion chambers. Dont have any eng pics with the PCV hooked up yet. Gotta take a few soon. Ron