Whipstock valve with nozzle bypass feature

A valve for subterranean whipstock service has a side port and a through passage with a biased movable sleeve to shift between circulation mode into the annulus and flow through mode for setting an anchor and then feeding window mill nozzles. The valve is run in when in circulation mode to allow operation of a measurement while drilling device. When the whipstock is properly oriented the pressure is increased to break a shear pin to allow a spring to bias the sleeve to the flow through position. The shifting of the sleeve opens a bypass passage around the restriction orifice that was first used to build pressure to break the shear pins that let the sleeve move under spring bias. As a result the spring can hold the sleeve in position despite high flow rates needed to remove cuttings from the mill as the window is opened.