Ford 2003 Mustang Workshop Manual page 922

SECTION 303-00: Engine System — General Information
GENERAL PROCEDURES
Valve —Seat Width
1. Measure the valve seat width. If necessary, grind the valve seat to specification.
Measure the intake valve seat width.
Measure the exhaust valve seat width.
Recheck the valve spring installed length after the seats have been ground, and shim the
valve springs as necessary to achieve the correct installed spring length.
Refer to the appropriate section in Group
2003 Mustang Workshop Manual
303 for the procedure.