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8-16
ing them with the valve closed. They
also can be checked with a dial indi-
cator (Fig. 21).
CYLINDER HEADS
CLEANING
With the valves installed to pro-
tect the valve seats, remove deposits
from the combustion chambers and
valve heads with a scraper and a
wire brush.
Be
careful not to damage
the cylinder head gasket surface.
After the valves are removed, clean
the valve guide bores with a valve
guide cleaning tool. Use cleaning
solvent to remove dirt, grease and
other deposits. Clean all bolt holes;
be sure the oil transfer passage is
clean.
FIG. 21 -Push Rod Runout
Remove all deposits from the
valves with a fine wire brush or buf-
fing wheel.
INSPECTION
Check the cylinder head for
cracks, and inspect the gasket sur-
face for burrs and nicks. Replace
the head if it is cracked.
The following
inspection pro-
cedures are for a cylinder head that
is to be completely overhauled. For
individual repair operations, use
only the pertinent inspection pro-
cedure.
Cylinder Head Flatness. When a
cylinder head is removed because
of gasket leaks, check the flatness
of the cylinder head gasket surface
(Fig. 22) for conformance to speci-
fications.
If
necessary to refinish the cylin-
der head gasket surface, do not
plane or grind off more
than
0.010
inch.
Vlllve Seat Runout. Check the
valve seat runout with an accurate
gauge (Fig. 23). Follow the instruc-
tions of the gauge manufacturer. If
the runout exceeds the wear limit,
reface the valve and valve seat.
Valve Seat Width. Measure the
valve seat width (Fig. 18). Reface
the valve seats if the width is not
within specifications.
Valves. The critical inspection
points and tolerances of the valves
are illustrated in Fig.
24.
Refe~
to
GROUP 8-
ENGINE
the specifications for the wear lim-
its.
Inspect the valve face and the
edge of the valve head for pits,
grooves, scores or other defects. In-
spect the stem for a bent condition
and the end of the stem for grooves
FIG. 22
-Typical Cylinder Head
Flatness
or scores. Check the valve head for
signs of burning, erosion, warpage
and cracking. Defects, such as minor
pits, grooves, etc., may be removed.
Discard valves that are severely
damaged.
Inspect the valve springs, valve
spring retainers, locks and sleeves
for defects.
Valve Face Runout. Check the
valve
face runout (Fig. 25). It
should not exceed the specified wear
limit.
If
the runout exceeds the wear
limits, the valve should be refaced
or replaced as outlined under Re-
facing Valves in Section 2.
Valve Stem Cleanmce. Check the
valve stem to valve guide clearance
of each valve in its resoective valve
guide with the tool shown in Fig. 26
or its equivalent.
Install the tool on the valve stem
until it is fully seated, and tighten
the knurled set screw firmly. Permit
the valve to drop away from its
seat until the tool contacts the
FIG. 23
-Typical
Valve Seat
Run out
upper surface of the valve guide.
Position the dial indicator with
its flat tip against the center portion
of the tool's spherical section at
approximately 90° to the valve
stem axis. Move the tool back and
forth in line with the indicator
stem. Take a reading on the dial
indicator without removing the tool
from the valve guide upper surface.
Divide the reading by two, the
division factor for the tool.
Valve Sprlag Pressure. Check the
springs for proper pressure (Fig. 27)
at the specified spring lengths. Weak
valve springs cause poor engine
performance; therefore, if the pres-
FOR DIMENSIONS,
REFER TO
SPECIFICATIONS
VALVE
FACE
ANGLE
FIG. 24 -Critical Valve Tolerances
mre of any spring approaches the
wear limit, replace the spring.
Valve Sprlag SquareDess. Check
each spring for squareness using a
steel square and a surface plate
(Fig. 28). Stand the spring and
square on end on the surface plate.
Slide the spring up to the square.
Revolve the spring slowly and ob-
serve the space between the top
coil of the spring and the square.
If
FIG. 25 -Valve Race Runout
the spring is out of square more than
*e inch, replace it.
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