Chevrolet 10 Series 1968, Service Manual

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ENGINE 6-16
installed, coat foot of valve lifters with Molykote
or its equivalent.
2. Install push rod covers, using new gaskets, and
torque to specifications.
3. Install distributor, positioning rotor to number one
cylinder position, then connect primary lead at coil.
4. Install and adjust valve mechanism as outlined.
5. Adjust ignition timing and carburetor idle speed and
mixture.
Valve Stem Oil Seal and/or Valve Spring
Replacement
1. Remove rocker arm cover as outlined.
2. Remove spark plug, rocker arm and push rod on the
cylinder(s) to be serviced.
3. Apply compressed air to the spark plug hole to hold
the valves in place.
NOTE:
A tool to apply air to the cylinder is
available through local jobbers or may be manu­
factured. In manufacturing this tool a AC-46N
Spark Plug or its equivalent is recommended.
This will make the tool universal for all Chevro­
let engines. Chisel the spark plug as shown,
then drive the porcelain out of the plug by tap­
ping the center electrode against a hard block.
Using a 3/8" pipe tap, cut threads in the re ­
maining portion of the spark plug and assemble
as shown (fig. 3L).
4. Using Tool J-5892 to compress the valve spring,
remove the valve locks, valve cap (or rotator) valve
shield and valve spring and damper (fig. 4L).
5. Remove the valve stem oil seal.
6. To replace, set the valve spring and damper, valve
shield and valve cap (or rotator) in place. The close
coiled end of the spring is installed against the cyl­
inder head. Compress the spring with Tool J-5892
and install oil seal in the lower groove of the stem,
making sure the seal is flat and not twisted.
NOTE: A light coat of oil on the seal will help
prevent twisting.
7. Install the valve locks and release the compressor
tool, making sure the locks seat properly in the
upper groove of the valve stem.
NOTE:
Grease may be used to hold the locks
in place while releasing the compressor tool.
F ig . 3 L —A ir Adapter Tool
1. Place the gasket in position over the dowel pins with
the bead up.
2. Carefully guide cylinder head into place over dowel
pins and gasket.
3. Coat threads of cylinder head bolts with sealing
compound and install finger tight.
4. Tighten cylinder head bolts a little at a time in the
sequence shown on the torque sequence chart until
the specified torque is reached.
5. Install coil (if removed).
6. Connect upper radiator hose and engine ground strap.
7. Connect temperature sending unit wires and install
fuel and vacuum lines in clip at water outlet.
CHEVROLET TRUCK SERVICE MANUAL
F ig .
4 L —
Compressing V a lv e Spring
8. Install spark plug, using a new gasket, and torque to
specifications.
9. Install and adjust valve mechanism as outlined.
Cylinder Head Assemblies
Rem oval
1. Remove manifold assembly as outlined.
2. Remove valve mechanism as outlined.
3. Drain cooling system.
4. Remove fuel and vacuum line from retaining clip
at water outlet then disconnect wires from tempera­
ture sending units.
5. Disconnect upper radiator hose at water outlet hous­
ing and battery ground strap at cylinder head.
6. Remove coil.
7. Remove cylinder head bolts, cylinder head and gas­
ket. Place cylinder head on two blocks of wood to
prevent damage.
Installation
C A U TIO N :
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 bolt must be cleaned. (Dirt
will affect bolt torque). Do Not use gasket sealeF
on composition steel asbestos gaskets.