Chevrolet 10 series 1973, Руководство по капитальному ремонту

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E N G IN E 6 -1 3
Fig. 21 —In sta llin g Rocker A rm Stud (In-Line and
"S m a ll V 8 ")
the head is imperative to insure that the heat in the valve
head will be properly carried away.
Several different types of equipment are available for
reseating valves seats. The recommendations of the
manufacturer of the equipment being used should be
carefully followed to attain proper results.
Regardless of what type of equipment is used, however,
it is essential that valve guide bores be free from carbon
or dirt to ensure proper centering of pilot in the guide.
1. Install expanding pilot in the valve guide bore and
expand pilot.
2. Place roughing stone or forming stone over pilot
and just clean up the valve seat. Use a stone cut to
specifications.
3. Remove roughing stone or forming stone from
pilot, place finishing stone, cut to specifications,
over pilot and cut just enough metal from the seat
to provide a smooth finish. Refer to specifications
and Figure 23.
4. Narrow down the valve seat to the specified width.
NOTE: This operation is done by grinding
the port side with a 30 degree stone to lower
seat and a 60 degree stone to raise seat.
5. Remove expanding pilot and clean cylinder head
carefully to remove all chips and grindings from
above operations.
6. Measure valve seat concentricity (fig. 24).
NOTE: Valve seats should be concentric to
within .002" total indicator reading.
Valves
Valves that are pitted can be refaced to the proper angle,
insuring correct relation between the head and stem on a
valve refacing mechanism. Valve stems which show
Fig. 2 2 —Ream ing Valve Guide
excessive wear, or valves that are warped excessively
should be replaced. When a valve head which is warped
excessively is refaced, a knife edge will be ground on
part or all of the valve head due to the amount of metal
that must be removed to completely reface. Knife edges
lead to breakage, burning or pre-ignition due to heat
localizing on this knife edge. If the edge of the valve
head is less than 1/32" thick after grinding, replace the
valve.
Several different types of equipment are available for
refacing valves. The recommendations of the manufac­
turer of the equipment being used should be carefully
followed to attain proper results.
1. If necessary, dress the valve refacing machine
grinding wheel to make sure it is smooth and true.
Set chuck at angle specified for valve. Refer to
specifications and Figure 23.
2. Clamp the valve stem in the chuck of the machine.
3. Start the grinder and move the valve head in line
with the grinder wheel.
4. Turn the feed screw until the valve head just
contacts wheel. Move valve back and forth across
the wheel and regulate the feed screw to provide
light valve contact.
5. Continue grinding until the valve face is true and
smooth all around the valve. If this makes the valve
head thin (1/32" min.) the valve must be replaced
as the valve will overheat and burn.
6. Remove valve from chuck and place stem in "V"
block. Feed valve squarely against grinding wheel
to grind any pit from rocker arm end of stem.
NOTE: Only the extreme end of the valve
OVERHAUL MANUAL