Chevrolet 1973 Overhaul Manual page 152

Fig. 14—Cleaning C om bustion Chambers
2. Thoroughly clean the valve guides using Tool
J-8101 (fig. 15).
3. Clean all carbon and sludge from push rods, rocker
arms and push rod guides.
4. Clean valve stems and heads on a buffing wheel.
5. Clean carbon deposits from head gasket mating
surface.
Inspection
1. Inspect the cylinder head for cracks in the exhaust
ports, combustion chambers, or external cracks to
the water chamber.
2. Inspect the valves for burned heads, cracked faces
or damaged stems.
NOTE: Excessive valve stem to bore clear­
ance will cause excessive oil consumption and
may cause valve breakage. Insufficient clear­
ance will result in noisy and sticky function­
ing of the valve and disturb engine
smoothness.
3. Measure valve stem clearance (fig. 16) as follows:
Clamp a dial indicator on one side of the cylinder
head rocker arm cover gasket rail, locating the
Fig. 15—Cleaning Valve Guides
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. With the valve
head dropped about 1/16" off the valve seat; 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. 17).
NOTE: Springs should be compressed to the
specified height and checked against the
specifications chart. Springs should be re­
placed if not within 10 lbs. of the specified
load (without dampers).
5. Inspect rocker arm studs for wear or damage.
Inspect push rod guides on Mark IV V8 engines for
wear or damage.
Repairs
Rocker Arm Studs and Push Rod Guides
M ark IV and 3 5 0 cu. in. High Performance
The push rod guides are related to the cylinder head by
the rocker arm studs (fig. 18). Replace where necessary
and torque rocker arm studs to specifications.
NOTE: Coat Threads on cylinder head end
of rocker arm studs with sealer before
assembling to cylinder head.
Fig. 16—M easuring Valve Stem Clearance
E N G IN E 6-11
OVERHAUL MANUAL