Mercury 5 SERIES Service Manual page 126

CYLINDER HEAD
Condition: Valve seat is too narrow and is located near the bottom edge of the valve face.
Valves
1. Clean the carbon deposits from the valve. Discard any cracked, warped, or burned
valves.
2. Measure the valve stem diameter to check for wear. Replace valves if not within specifi-
cation.
a
a -
Intake Valve
Exhaust Valve
3. Check the valve face for pitting. Valve faces that are pitted must be replaced or refaced.
NOTE: Several different types of equipment are available for refacing valves. Follow the
equipment manufacturer's instructions.
Page 4A-18
Valve Seat Cutter Set
60 Cutter, First
Use Use
45 Cutter
Valve Stem Diameter
Valve Stem Diameter
Standard Value
0.216 in. (5.48 mm)
0.214 in. (5.44 mm)
55802
Desired Results
To center the seat and to increase To center the seat and to increase
its width
55810
Out of limit to use; replace valve
0.2145 in. (5.45 mm) or less
0.213 in. (5.41 mm) or less
90-857138R1 MAY 2000