Documents steps to disassemble the upper and lower intake of a 2002 duratec 3 0l engine. Duratec is a brand name of the ford motor company used for the company s range of gasoline powered four cylinder five cylinder and six cylinder passenger car engines. The valve stem diameter is 5 975 to 5 995 mm for the 35 mm intake valves and 5 950 to 5 970 mm for the 30 mm exhaust valves with 0 05 mm of valve face runout and a valve face angle of 45 5 degrees.