The Stovebolt Site Forums The Shop Area The HiPo Shop SBC Breather Function

If that larger nipple on the front of the carb is manifold vacuum, which I think it is, then either the brakes or the PCV could go there. Turn the carburetor upside down and trace that nipple and its passageway and see if it goes straight through the base of the carb underneath the throttle butterflies, if so, it's manifold vacuum. You could then research a normal old style threaded PCV valve to fit the rear port and run a hose from there to the rear of the engine block. Then the hose from the valve cover to the base of the air cleaner. The threaded port on the rear would probably be 3/8" pipe thread but you'll want to confirm that. Several PCV valves came up on a search that have male thread x hose barb.