In a rotary valve including a housing having a rotor chamber and a drive shaft journaled in the housing and having an end portion thereof projecting into the rotor chamber, a rotor mountable on the drive shaft within the rotor chamber comprising a solitary body of plastic material having a cylindrical wall provided with a plurality of circumferentially spaced pockets machined-out therein, means for detachably mounting the body on the drive shaft and means for securing the body to the drive shaft when mounted thereon.