Abstract: An automotive type internal combustion engine has a positive crankcase ventilation (PCV) valve metering the flow of engine blow-by gases and fumes from the engine crankcase to the intake manifold, the valve having a sonic flow passage providing flow over the entire part throttle operating range of the vehicle to provide a precise flow and predictable calibration of the flow.

Abstract: A variable area venturi carburetor has a wall movable by a servo controlled by venturi-like control vacuum to vary the area and thereby change airflow capacity and fuel flow; a tapered fuel metering rod is attached to the wall and cooperates with a stationary fuel jet; during cold engine operation, a temperature responsive device progressively blocks the flow of the control vacuum as the temperature decreases, to permit higher ported manifold vacuum also acting on the servo to open the venturi wider to change the fuel metering signal while withdrawing the fuel metering rod, to provide a change in richness. Return to normal temperature causes the control vacuum to bleed the ported manifold vacuum to the control vacuum level.