Westerbeke WPDS-20 Technical Manual page 43

A20
CYLINDER HEAD
1. Detach the spring clips from the valve cotters.
2. Remove the valves and their components, using
tool 18G 106.
3. Renew the valve spri ngs if they are not as specified
in Data.
4. If the valve gUides are worn, drive them out
through the upper face of the cylinder head. Fit
new valve gUides through the ports and drive them
in to the position shown in Data.
5. Ream the gUides to the dimensions given in Data.
6. If necessary, regrind the valves to the angle given
in Data and reface the valve seats with the tools
listed in 'SERVICE TOOLS'.
7. Lap the valves onto their seats, using tool18G 29.
8. Check the valve head stand-down (see Data). If
stand-down is excessive, even with a new valve
fitted, machine the cylinder head (see Data) and
fit valve seat inserts. Inserts should also be fitted
if normal refacing will not restore the seats.
9. Renew the valve stem oil seals, and reassemble the
valve components to the cylinder head as shown in
Fig. 1.
Data
Valve springs
Free length ..
Fitted length
Pressure (valve closed)
Working coils
Wire diameter
Core diameter
Valve gUides
Fitted position
A=·75:::::~6
in.
(19·05::::~
mm.)
...s--.
t
clio
./-\
f~
~---
Inner
2·187 in. (55·55 mm.)
1·5 in. (38·1 mm.)
23 to 25 lb. (10·43 to
11·34 kg.)
71
·104 in. (2·65 mm.)
·75 to ·765 in. (19·05 to
19·43 mm.)
Fig. 1
Outer
2·5 in. (63·5 mm.)
1·703 in. (43·26 mm.)
56·5 to 60·5 lb. (25·63 to
27·44 kg.)
5t
·156 in. (3·96 mm.)
1·125 to 1·140 in. (28·58
to 28·96 mm.)
A