VALVES, REPAIR
NOTE:
Before any work is performed on valve
faces and seats, make sure clearance of valve stems
in their valve guides is within specifications.
A correction for minimum wear and damage to
valve and seat can be done by a process called lap-
ping. When th valve seats are lapped, keep valve
faces and seats within the specifications. Make sure
all of the lapping compound is removed from the
valve and valve seat when the process is completed.
Valves with minor pits in valve faces can be ma-
chined to proper angle. There are many different
types of equipment for repairing valve faces. Follow
instructions of manufacturer of equipment that you
are using. Valves must be machined to proper spec-
ifications. See Figure 15.
NOTE:
SEAT WIDTH DIMENSION APPLIES TO THE
46° FACE ONLY.
1. CYLINDER HEAD
Figure 15. Valve Seat Specifications for Inlet and
Exhaust Valves
Replace a valve if any of the following conditions
are present:
• Valve stem is worn below specifications.
• Valve stem is bent.
• Valve face is warped.
• Any part of valve is cracked.
• Any wear or damage to valve face that can-
not be removed by resurfacing and still meet
specifications shown in Figure 16.
Figure 16. Valve Head Measurements
VALVE SEATS, REPAIR
NOTE:
Before any work is done on valve faces and
seats, make sure clearance of valve stems in their
valve guides is within specifications.
Damaged valve seats can be resurfaced with a tool
that is designed to repair valve seats. There are
many different types of equipment for repairing
valve seats. Follow the instructions of the manufac-
turer of the equipment that you are using.
The valve seats are ground at three different an-
gles: 30°, 46°, and 60°. This method makes a valve
seat that is proper width and produces the correct
contact line between the valve and valve seat. The
specifications for valve seats are shown in the En-
gine Specifications section and in Figure 15.
• If contact line is too high, it can be made
lower by using a 30° stone.
• If contact line is too low, it can be raised us-
ing the 46° stone.
• If seat is too narrow, it can be made wider
using a 46° stone.
• If seat is too wide, it can be made narrower
using a 60° stone.
The correct dimensions for the valve seat widths
and valve/valve seat overlap are shown in Fig-
ure 17. The valve seat widths are the dimensions of
46° face only. The valve/valve seat overlap is dis-
tance from the edge of the seat to outside edge of
valve.
0600 SRM 1251
Cylinder Head Repair
11
