An electromagnetic fuel injector for use in an internal combustion engine has a center pole piece with an axially extending bore which slidingly accepts an adjusting pin therein. The adjusting pin has a first end portion for engagement with the armature return spring of the injector. Axial translation of the adjusting pin, relative to the center pole piece will vary the compression on the spring, the seating load on the armature valve and, as such, the dynamic flow characteristic of the injector. The adjusting pin further has means for engaging the center pole piece to rotate the piece which is threadingly engaged within the injector housing. Rotation of the threaded piece relative to the housing varies the armature/valve travel and, as such, the static flow characteristic of the injector.