Chevrolet 1980 Light Duty Truck Service Manual page 503

follows:
a. Clamp a dial indicator on one side of the cylinder
head rocker arm cover gasket rail.
b. Locate the indicator so that movement of the valve
stem from side to side (crosswise to the head) will cause a
direct movement of the indicator stem. The indicator stem
must contact the side of the valve stem just above the valve
guide.
c. Drop the valve head about 1/16" (1.6mm) off the
valve seat.
d. Move the stem of the valve from side to side using
light pressure to obtain a clearance reading. If clearance
exceeds specifications, it will be necessary to ream valve
guides for oversize valves as outlined.
4. Check valve spring tension with Tool J-8056 spring
tester (fig. 6A5-22). Springs should be compressed to the
specified height and checked against the specifications
chart. Springs should be replaced if not within 10 lbs. (44
N) of the specified load (without dampers).
5. Inspect rocker arm studs for wear of damage.
Inspect push rod guides for wear or damage.
Assembly
1. Insert a valve in the proper port.
2. Assemble the valve spring and related parts as
follows:
a. Install valve spring shim on valve spring seat then
install a new valve stem oil seal over valve and valve guide.
b. Set the valve spring (with damper); and valve cap
in place (fig. 6A5-23).
c. Compress the spring with Tool J-8062.
d. Install the valve locks and release the compressor
tool, making sure the locks seat properly in the groove of
the valve stem. Grease may be used to hold the locks in place
while releasing the compressor tool.
Fig. 6A5-23~Valve Spring Installation
3. Install the remaining valves.
4. Check the installed height of the valve springs, using
a narrow thin scale. A cutaway scale will help (fig. 6A5-24).
Measure from the top of the shim or the spring seat to the
top of the valve spring or valve spring shield (fig. 6A5-25).
If this is found to exceed the specified height, install a valve
spring seat shim approximately 1/16" (1.6mm) thick. At no
time should the spring be shimmed to give an installed
height under the minimum specified.
Installation
• The gasket surfaces on both the head and the block
must be clean of any foreign matter and free of nicks or
heavy scratches. Cylinder bolt threads in the block and
threads on the cylinder head bolts must be clean as dirt will
affect bolt torque.
1. On engines using a STEEL gasket, coat both sides
of a new gasket with a good sealer. Spread the sealer thin
and even. One method of applying the sealer that will assure
the proper coat is with the use of a paint roller. Too much
sealer may hold the gasket away from the head or block.
• Use no sealer on engines using a composition STEEL
ASBESTOS gasket.
2. Place the gasket in position over the dowel pins with
the bead up.
3. Carefully guide the cylinder head into place over the
dowel pins and gasket.
4. Coat threads of cylinder head bolts with sealing
compound, # 1052080 or equivalent, and install bolts finger
tight.
5. Tighten each cylinder head bolt a little at a time in
the sequence shown in figure 6A5-26 until the specified
torque is reached.
GRIND OUT THIS PORTION
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Fig. 6A5-24~Cutaway Scale
MARK IV 6A5-15
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LIG H T TRUCK SER V IC E M ANUAL
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