F 550 4WD Super Duty V10-6.8L VIN S (2000)
5. Coat the threads of the mandrel with cutting oil.
6. Thread the tapersert onto the mandrel until one thread of the mandrel extends beyond the tapersert.
7. Note: A correctly installed tapersert will be either flush with or 1.0 mm (0.039 inch) below the spark plug gasket seat.
Tighten the tapersert into the spark plug hole.
8. Turn the mandrel body approximately one-half turn counterclockwise and remove.
9. Use the Feeler Gauge and a suitable straightedge to check for cylinder head flatness.