Abstract: A rotary valve assembly for fuel injectors which can effectively prevent highly pressurized drain waves from propagating into an extended metering groove. The assembly comprises a cylindrical housing having a plurality of fuel ports formed in the cylindrical wall and a metering port formed in the end wall, each of the fuel ports being connected with respective fuel injectors, and a rotary spool rotatably mounted within the housing defining a metering chamber between one end face thereof and the end wall of the housing. The rotary spool has formed therein a fuel supply passage connected at one end with a fuel supply source and at the other end selectively connectible with either one of the fuel ports. The rotary spool further has formed therein an extended metering groove and a drain groove spaced circumferencially from the metering groove.