Fuel injector nozzles

An internal combustion engine fuel injector having a selectively openable nozzle through which fuel is delivered to a combustion chamber of the engine, said nozzle comprising a port having an internal annular surface and a valve member having an external annular surface co-axial with respect to the internal annular surface, said valve member being axially movable relative to the port to selectively provide between said internal and external annular surfaces a continuous passage for the delivery of fuel therethrough or sealing contact therebetween along a circular seat line substantially co-axial to the respective annular surfaces to prevent the delivery of fuel therebetween, said annular surfaces-being relatively configured so that when the internal and external annular surfaces are in sealing contact along said circular seat line said seat line is located adjacent the downstream end of the passage with respect to the direction of the flow of fuel through the passage, and the maximum width of the passage between said annular surfaces is not substantially more than 30 microns.