Variable displacement valvetrain systems with rocker shaft porting and insert sleeves for engine cylinder deactivation

A valvetrain control system includes a rocker shaft that attaches to an engine assembly and includes an internal bore that receives hydraulic fluid. An oil control valve (OCV) is attached to the rocker shaft and fluidly coupled to the internal bore to receive therefrom hydraulic fluid. Pivotably mounted onto the rocker shaft is a rocker arm with opposing ends thereof that mate with a pushrod and a valve. The rocker arm includes a spring lock unit that attaches to the pushrod and fluidly couples to the OCV to receive hydraulic fluid and thereby drivingly disengage the rocker arm from the pushrod. An insert sleeve mounted in the internal bore receives hydraulic fluid from the rocker shaft. The insert sleeve includes a feed port that transmits hydraulic fluid from the insert sleeve to the OCV, and a feed pocket that transmits hydraulic fluid from the OCV to the spring lock unit.