Abstract: A tapered rotary valve plug is provided with an operating head and handle assembly for rotating and axially shifting the valve plug relative to its seat. Cam means is provided to shift the operating head and valve plug axially as a unit as the head is rotated. The operating head and handle assembly are coupled for movement as a unit. The handle assembly is provided with a manually actuated locking pin whereby the handle assembly and operating head may selectively engage the valve plug for rotation to either open or closed position. When the locking pin is disengaged from the valve plug, the handle assembly remains coupled to the operating head enabling rotation of the head independently of the plug and through the aforesaid cam means the plug may be either displaced from its seat to facilitate rotation to the desired valving position or forced into a positive tight sealing engagement with its seat after movement of the plug to the desired valving position.