Mercury 40 Service Manual page 229

Valve Seat Reconditioning
Clean the carbon deposits from the combustion chambers and valve seats and check for
pitting.
Several different types of equipment are available for reseating valve seats. Follow the
equipment manufacturer's instructions.
Measure valve seat width (a). Resurface the valve seat If not in specification.
If resurfacing the valve seats is required, resurface the valve seats to the specified angles
shown in chart.
90-828631R3 MARCH 1999
Valve Seat Width Specification "a"
Intake Valve
Exhaust Valve
c
Valve Seat Angle Specifications
a
b
c
a
55799
0.035 - 0.043 in. (0.9 - 1.1 mm)
b
a
55798
15
45
60
CYLINDER HEAD
Page 4A-33