Exhaust Emissions System - Crankcase Ventilation: Operation

When engine is in the closed throttle position the blow-by gases are drawn into the intake manifold through the calibrated orifice of control valve in the carburetor. As the throttle is opened, part of the blow-by gases are drawn into the intake manifold through the open duct of the control valve. The rest of the blow-by gases flow directly to the clean side of the air cleaner.