and 2 7/8 inches for the exhaust valve
(6) Remove the water pump (par. 46).
guides.
Note. If only the rear cylinder head as-
sembly is being removed it is not necessary
( 3 ) Valve seat inserts are used only for
to remove the water pump.
the exhaust valves, and are held in
(7) Remove the rocker arm assemblies
place by a shrink fit. Inspect all ex-
( p a r . 74).
haust valve inserts in the cylinder
(8) Refer to figure 23, and remove the cyl-
h e a d and replace any that are loose,
inder head assembly from the engine.
c r a c k e d , or otherwise damaged. It is
not recommended to install a new in-
b. Disassembly. Refer to figure 25, and dis-
sert having the same outside diameter
assemble the cylinder head assembly.
a s the one removed. When replacing
an oversize insert, clean and rema-
79. Cylinder Head Assembly Cleaning,
chine the counterbore for a 0.010 inch
Inspection, and Repair
l a r g e r insert than the one removed.
Use a tool with a correct fitting pilot.
a. Cleaning.
W h e n machining the counterbore, be
sure to go deep enough with the tool
(1) Clean all parts in an approved clean-
i n g solvent. Be sure all oil galleries
to clean the bottom so that the insert
are open and clean.
w i l l have full contact to carry away
the heat, The outside diameter of the
(2) Clean all valve stem guides, removing
inserts is 2.2545 to 2.2535 inches.. The
lacquers or other deposits by running
inside diameter of the counterbore is
a valve guide cleaner or wire brush
2.251 to 2.250 inches. A press fit
through the reamed hole.
would be 0.0067 to 0.0052 inch.
( 3 ) Clean the inside chambers and pas-
(4) The new insert, when installed, should
sages of the energy cell, using scraper
have a press fit. Chill the insert in a
and drill.
container of dry ice for 20 minutes
before installing.
b. Inspection and Repair.
( 5 ) Inspect valves for condition and re-
(1) Inspect the guides for wear by using
place any that are nicked, cracked,
a telescopic gage and a l-inch mi-
burned, and those on which the valve
crometer. Replace all guides that are
stems are bent or worn more than
worn more than 0.0015 inch in diame-
0 . 0 0 2 inch. Replace or reface all de-
t e r . The maximum length for the in-
fective valves.
take valve stem guides is 4.718 inches,
(6) Install the pilot in the valve stem
t h e maximum length for the exhaust
valve guides is 3.812 inches. The
guide. Set the stone to an angle of
45 on the valve reseating outfit. Place
valve guide stem hole diameter for
t h e grinder and stone assembly over
the intake valve is from 0.4985 to
the pilot on the valve guide and grind
0.4990 inch and for the exhaust valve
just enough to remove all pits and
i s from 0.4985 to 0.4995 inch. The
grooves and to have a new cut show
outside' diameter for both the intake
evenly all around the seat. Check the
and exhaust valve guides is from
seat for concentricity with a dial
0.8755 to 0.8765 inch.
indicator.
( 2 ) The old valve guides are pressed out
(7) Install the valves in a suitable grinder
of the cylinder head by pressing from
making sure the grinding wheel is
the combustion chamber side. The new
properly true and the chuck is set at
valve guides are pressed in from the
the proper angle. Care should be
c o m b u s t i o n chamber side to a depth
t a k e n while grinding not to remove
below the cylinder head surface of, 2
too much material from the face.
inches for the intake valve guides,
64
AGO 8498A
