Generac Power Systems OHVI GSH 190, Service Manual

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6-
SeCTIoN 6: CYlINder HeAd ANd vAlveS
vAlve ServICe (CoNTINued)
VALVE GUIDES:
Valve guides are permanently installed in the cylinder head
and cannot be replaced (see Figure 6-9).
At the time of this writing, oversize valves were NOT avail-
able. Thus, if valve guides are worn or damaged, the guides
cannot be reamed to accommodate an oversize valve stem.
VALVE GUIDES
Figure 6-9. Valve Guides
VALVE TAPPETS:
The valve tappets (Figure 6-
0) will be removed when
the camshaft is removed.
Intake and exhaust valve tap-
pets are identical. However,
once a wear pattern has
been established, the two
parts should not be inter-
changed.
Figure 6-10. Tappet
VALVE SPRINGS:
Inspect the valve springs (Figure
6-). Measure the spring FREE
LENGTH. Also measure the
spring length when a known
load is applied to the spring.
Refer to SPECIFICATIONS in
Section and 5.
Figure 6-11. Valve Spring
INSTAllATIoN
After the valve train components have been properly
inspected and serviced, install the components as follows:
. Install the intake and exhaust valves through the proper
valve guides in the cylinder head.
a. The exhaust valve has the smaller head.
b. The intake valve has the larger head.
c. Valve seat sizes will match their respective valve
head sizes.
d. The exhaust valve stem is smaller than the intake
valve stem.
NOTE: Be sure to lubricate valve stems and valve guides
before assembly!
2. The intake valve has a valve stem seal.
a. Install the intake valve stem seal.
b. Install the valve spring washer, the valve spring and the
valve spring retainer.
c. Install the valve spring keepers.
NOTE: To install valve spring keepers, use the valve
spring compressor to compress the spring enough to
insert one keeper half. Compress the spring again to
insert the other keeper half.
. The exhaust valve does not have a valve stem seal.
a. Install the valve spring washer, valve spring and valve
spring retainer.
b. Install the valve spring keepers.
. After both valves have been properly installed in the head,
position the new head gasket and install the cylinder
head.
NOTE: The head gasket is coated with a special substance
for better sealing. It must be free of nicks, scratches and
other defects, or leakage could result.
5. Install the cylinder head bolts and tighten them in the
sequence shown in Figure 6-.
6. Position the push rod guide plate on the head. Then install
the rocker arms and pivot ball studs. Install the jam nuts far
enough to hold the guide plate in position. Valve clearance
will be adjusted later.
7. Rotate the rocker arm as shown in Figure 6-5 to install the
push rod. Insert the push rod through the push rod guide
plate, with either end resting against the tappet. Place the
rocker arm over the push rod. Alignment is correct when
push rod ball rests in the rocker arm socket.
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