An electromagnetic fuel injector and novel method for assembly and calibration having a solenoid assembly with a pole piece, a valve assembly including an armature, and a working air gap separating the valve assembly from the pole piece when the injector is in a de-energized state. A shim having a thickness equivalent to the length of the working air gap is placed between the pole piece and the valve member during construction of the injector. Following assembly, a solvent is introduced into the injector to dissolve the shim, which is constructed of a material readily dissolvable in the desired solvent, to define the working air gap and, therefore, the static flow through the injector.