Today I completed adjustment of the compression ring gaps for the second piston groove, and couple for the top groove that were right at the specified minimum end gap of 0.013”. I clamped a fine file between two 1.5" wide aluminum angles in a vice, to support the rings perpendicular to the file. The ring is then squeezed together against the file and pushed forward, so the filing action is toward the center of the ring. The squeezing force is released when the ring is retracted in preparation for the next stroke.
Be sure to keep the ring centered on, and flat against the supporting surface so the gap angle is unchanged.
After every ten or twelve strokes, the gap is deburred and inserted in the piston to check the results.
