according to the present invention , a cross over nozzle is provided of two parts which , when joined , define a housing having a passage extending therethrough , a tapered valve seat extending about the passage and a value member having a tapered valve head disposed in the passage for engaging the valve seat . the two parts are axially separable at an interface extending through the valve seat / valve head . in order to open the valve , both valve parts are first joined and then moved together as one member in the same direction relative to the housing axially away from the valve seat . similarly , the valve members are jointly moved into engagement with the valve seat before the cross over nozzle is separated . accordingly , unlike the valve gate design , the valve interface between the two parts of the valve head isn &# 39 ; t exposed to molten resin and therefore molten resin isn &# 39 ; t trapped therebetween to cause a string upon opening .