Westerbeke 8.0KW-60Hz Service Manual page 24

(
ENGINE INSPECTION '
0.39±,0.02o In
(io±0.5 mm)
VALVE
GUIDE~t7r..."._-,·_......;t,-'
_" _"
CYLINDER HEAD '
--}
HEIGHT TO THE TOP OF THE VALVE
NORMAL SIZE 0.39 in (lOmm)
c. Valve guide replacement.
e
'"
:.
.e
ill
. .
(1)
Remove the guide from the cylinder head by
pushing it with a tool and an arbor press from the
bottom side of the head.
(2)
Install a new guide into the cylinder head by
pushing it with an arbor press from the upper side
of the head until the specified height to the top of
the guide is obtained.
(3) Insert a new valve into the guide and make sure the
valve slides in the guide freely.
(4) Mter the valve guide has been.replaced, check the
valve contact with its seat.
(5) Put
a small amount of Prussian blue or read lead on
the valve face. Hold the valve with a valve lapping
tool (commercially available) and press it against
, the seat to check its contact.
LAPPING THE
VALVE IN THE
SEAT
/
(6) The width of contact must be uniform all the way
around both seat and valve. If the contact is bad,
reface the valve and seat
(7) If the valve margin (valve lip thickness) exceeds the
limit, replace the valve.
VALVE MARGIN (LIP) THICKNESS
STANDARD 0.039 In (l.omm)
LIMIT 0.020 In (0.5mm)
'(8) If the valve sinkage (the dimension from the top of
a:
closed valve to the face of cylinder head)
,exceeds the lintit, recondition the valve seat or
replace the cylinder head assembly.
VALVE SINKAGE'
STANDARD
LIMIT
0.020
±
0.0098io (0.5
±
0.25mm)
0.05910 (1.5mm)
GOOD
CONTACT MUST BE UNIFORM
AROUND THE COMPLETE
CIRCUMFERENCE
VALVE AND VALVE SEAT CONTACT
6. Valve refacing.
a. Set the valve n;facer at an angle of 45° and grind the
v a l v e . ' '
b. The valve margin must not be less than the limit. If the
margin seems to be less than the limit when the valve
is
refaced, replace the valve.
7. Valve
seat refacing.
a.
Before refacing the valve seat, check the clearance
between the valve and guide, and replace the guide if
necessary,"
b. Curthe valve seat with a valve seat cutter
(commercially availlible), or grind it with a valve seat
grinder, and finish the width of valve seat and the angle
of seat face to the correct values.
ANGLE OF SEAT FACE: STANDARD 45"
WIDTH OF VALVE SEAT
STANDARD 0.051 - 0.071 In (1.3 -1.8mm)
LIMIT 0.098 In (2.5mm)
Engines
'&
Generators
18