Re: PCV valve
Essentially a PCV valve is a smog device. In the good old days, when pollution was king, motors vented their crankcase blow-by gasses out of a 'road draft' tube into the atmosphere.
The 'positive' in PCV refers to the fact that the vent hose is hooked to a manifold vacuum source so that the blow-by gasses and pressure build up are sucked back into the engine in an attempt to reburn them.
The check valve opens briefly every time that vacuum drops due to acceleration. Then it closes back up to prevent your engine from running hellaciously lean.
The type of vent that mkast is speaking of does not involve a PCV valve, it is more akin to the old road draft tube. The blow-by gasses and crankcase pressure are simply continuously vented to the topside of the carburetor via a fitting(s) on the outside of the spark arrestor, hoping that they will be injested.
