Whats the theory of operation on the PVC valve on the 230 engine? Was thinking at high vacuum, the valve would close or restrict air flow and at low vacuum it would open and suck through the crankcase. Factory unit on there, only closes at hi intake prressure,???? there is no seat inside the valve for the needle to sit against and close . Am I missing something here or what?

My main problem is bad idle, lif I plug the valve at the manifold it runs great. No amount of carb adjustment will make it idle smooth with the valve in the curcuit. Timing is good ignition system is good, just need to know how this vent system operates