[Rick Parker]

A manifold can be modified to house the PCV valve under the carb in the valley area, but the hose must be attached to a vacuum source within the manifold or to the base of the carburetor to function. Occasionally is was tied into an individual runner (not as desireable) because it caused that cylinder to run lean. There is not enough draw (vacuum) for the PCV to function if it is attached to the carburetor air filter. Each of the various PCV valves are manufactured with check valves within of varying weights which are engineered for different OEM applications, consisting of various cam timing, induction sizing, cubic inch displacement, and manifold design. The hose from the valve cover vent to the air filter allows filtered air to enter the crankcase through the hose attached to the breather (via the Carb air filter) and is then drawn into the intake system through the PCV valve. It is a closed sytem in its most advanced state.