Jeep UNIVERSAL CJ-2A - Page 42

'Jeep' UNIVERSAL and 'Jeep' DISPATCHER
D
have been refaced and then only when necessary.
The finished valve seat should contact the approxi-
mate center of the valve face. Check by applying
an extremely thin coat of pencil lead or bearing-
fitting blue to the seat. Then install and rotate the
valve with light pressure. Blue (or pencil marks)
will transfer to the face of the valve. If the blue
is near the top edge of the valve face, lower the
valve seat by using the valve seat relief counter-
bore. If the blue is transferred to the bottom edge
of the valve face, raise the seat by using the valve
seat narrowing cutter.
When the valve seat can no longer be corrected, it
is advisable to investigate installing seat inserts.
NOTE:· The insert should be sufficiently .cooled
to permit installation with light taps; excessive
driving of the insert may cock it in the counterbore
or crack the insert.
0-57. Exhaust Valve Seat Insert Replacement
Hardened valve seat inserts for exhaust valves were
installed in production beginning with engine S/N
3J-161344 (For CJ-2A, beginning with replacement
engine S/N RJ-297362). They will seldom require
replacement. To avoid damaging the block, remove
an insert with a tool designed for this purpose.
When installing a new insert, make certain the
counterbore is clean and smooth. Use a driver that
will keep the insert in true alignment with the bore.
Cool the insert and the installing tool with dry ice
for 30 minutes. Make certain the valve seat is fac-
ing out. Drive in the insert with the tool until it
bottoms in the counterbore. After installation,
grind the valve seat at an angle of 45° and then
check with a dial indicator as shown in Fig. 4 7.
D-58. Valve Guide Replacement
Damaged, loose, or worn valve guides must be re-
placed.
FIG. 49-REPLACING VALVE GUIDES
Should it be necessary to replace the guides, this in-
stallation can b~t be made by using Valve Guide
Driver tool W.:'238 as shown in Fig. 49. The old
guides are removed by driving them through the
block into the valve compartment. If this driver is
not: availa,ble a suitable puller ca,n be made from a
piece
of 2" [50,8 mm.) pipe, 6" [152,4 mm.]long and
%" [9,525 mm.) bolt 10" [254 mm.) to 12" [304,8
mm.]long with a threaded end, a small hexagon nut
which will pass through the hole in the cylinder
block and a 2" [50,8 mm.) washer with a %"
[9,525 mm.] hole in it.
When replacing the guides maximum engine per-
formance can only be secured when the top of the
exhaust guide is positioned 1" [2,54 em.] and that
of the intake 1%;" [3,33 em.] below the top face of
the cylinder block as shown in Fig. 50. The Valve
Guide Driver shown in Fig. 49 is equipped with
adapter rings which act as stops to correctly locate
the guides.
Should the standard driver be unavailable a substi-
tute may be made from a piece of %
11
[12,7 mm.]
round steel 6
11
[15 em.] long. Turn down one
end to %
11
[9,5 mm.] in diameter for a distance
of 2
11
[50,8 mm.] to form a pilot and shoulder.
Should this type driver be used it will be necessary
to measure to correctly locate the guides.
Run a reamer (Tool C-38) through the new guides
after they have been correctly positioned.
10445
FIG. 50-POSITION OF VALVE GUIDES
D-59. Tappets and Cover
The valve tappets are lubricated through oil
troughs cast in the crankcase. The troughs are
filled by oil sprayed from the connecting rod ends
and passages are drilled through the tappet guides
to carry the oil to the tappets. A groove around the
center of the tappet shank carries the oil up and
down the guide.
Check the threads and fit of the valve adjusting
screw in the valve tappets. The fit of a screw should
be such that a wrench is required to turn it into or
out of the tappet as these are of the self-locking
type. Replace the worn part, either the screw or the
tappet, or both, if there is looseness between the
parts.
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