The open tube just lets fumes pass through and out on their own. The
PCV, positive crankcase ventilation, uses intake manifold vacum to pull the fumes out of the block and valley pan and send them through the engine. Its the positive part that makes them worth the effort.
I had a mechanic show me a graphic demonstration on a Pinto 4cylinder car. It sounded good, idled fine, and drove without smoke. He pulled the PCV and blocked it and the car smoked BAD. Lots of blue oil smoke at idle. Quite impressive. Chuck
Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.
MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire