Jeep UNIVERSAL CJ-2A - Page 73

E
F4-134 ENGINE
E-52. Deleted.
E-53. Camshaft ahd Bearings
Th~ camshaft is supported at four points in the
cyhnder block. The front is supported in a re-
placeable, steel-shell, babbit-lined bearing. 'The
bearing is pressed into place. The. other three bear-
ing surfaces are· precision machined in the cylinder
block . .The ·camshaft bearings are pressure lubri-
cated through drilled passages in the crankcase.
End thrust of the camshaft is taken by a thrust
plate bolted to the crankcase. The camshaft is
driven by a silent helical-cut tooth timing gear at
the front of the engine. A worm gear, integral with
the camshaft, drives the oil pump and. distributor.
The fuel pump io actuated by an eccentric forged
onto the camsh-::.i"t. · ·
Clean the carrshaft thoroughly in cleaning solvent.
lrispect all cnmshaft bearing surfaces to determine
if they are scored or rough. The cam faces must be
perfectly smooth throughout their contact face
and must not be scored or worn. '
E-54. Camshaft Front Bearing Replacement
Use a suitable driver to remove the carn:shaft front
bearing from the cylinder block. To install a new
bear~ng, align the oil hole in the .bearing with the
bored oil hole i~ the cylinder block and drive the
bearing. in· until the fr.ont end of the bearing is
flush w1th
the front surface of the cylinder block.
Make sure the oil hole is open and clear. It is not
necessary to line-ream the bearing after installation
because bearings for replacement are precision
reamed to the finished size. Do not stake the
bearing. . · ·
E•55. Camshaft End Play .
End play of the camshaft is determined by running
clearance between the rear face of the camshaft
gear and ~he tqru,st plate and .is establisl:led by the
spacer thickness. The standard clean·: -~e is ~004 II
tq .007
11
[<l,102 a 0;178 riim;] and can be measured
by a dial indicator. A~ a general rule this clearance
will cliange· but little t.P.rough wear or when a new
gear is instalh!d. To ··predetermine the correct end
fl9at with the gear, spacer, and thrust plate re-
moved, measure the thickness of both the thrust
plate and spacer witl;i a micrometer. The thickness
of the spacer should "be approximately .006
11
[0,152 mi?.J. greater than that of the .thrust plate.
When th1s 1s ·correct ~nd the parts are assembled
and drawn tight1y together by. the gear retaining
scr.e1'1'; :t;he and play ·should come within standard
limits .. : : , .. , · ·•·· .. . · · · ·
E-55~- Timinli::Gears and Cover·
The timing gear{ are- mounted at the front of 'the
epg~ne. Ca,mshaft dri~e i!(' throtigh' helical-cut
tlmmg . gears; a steel· gear. on the crariksllaft and a
pressed fiber
~ear on,. 'the camsh~tft. The· gears are
keyed to the1r respective shafts. The camshaft
driven gear is secured , on the front end of the
camshaft by means of · a capscrew and a plain
washer. The crankshaft gea,r is secured on the
front end of the crank$haft by a nut threaded onto
the front end ofthe crankshaft holding the crank-
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shaft pulley, crankshaft oil: slinger, and l:he crank-
shaft· drive gear spacer. The timing gears are
lubricated through a jet threaded into the crank-
case directly above the gear contact and oils1,1pplied
through a drilled passage' from . the front main
bea~,:ing. The timing geani are . enclosed . by the
sealed timing cover. The oil seal in the co.ver bears
against th;e hub of the crankshaft pulley, Timing
gears are ,accessible for inspection or replacement
with . the engine installed in the vehicle after re"
moving the radiator, belt drive pulley, and timing··
cover.
Should it be necessary to replace the timing gears
attention must be given to the end float of both
the . camshaft and crankshaft and to the running ·
clearance of both gears. It is also advisable to
check both the oil jet and oil passage to the crank~
shaft front beadng to be, sure that they are clear.
E-57, Inspection and Repair·
Ch.eck the general condition of both gears and
inspect for evidence of excessive wear. Replace
excessively worn or damaged· gears. Inspect the
cover and replace if bent or damaged. It is recom-
mended that the crankshaft oil seal in the cover
be replaced when the cover is removed tb ensure a
good seal around the crankshaft. To replace this
seal wi~~ the engine in the vehicle requires removing
the rad1ator and water pump.
E-58. Valves, Springs, and Guides
The exhaust valves seat on the top of.the cylinder
block with the stems extending down through .
replaceable valve guides. The exhaust valves are
actuated by the camshaft through exhaust vaive
tappets. The exhaust 'valve springs are assembled
and locked on the lower end of the exhaust valve
ste!lls. The retaining locks are the split type, which
fit m a recess on the valve stems and into the taper
in the valve spring retainers.
Adjustment of exhaust valves is by means of the
adjusting screw threaded into the upper end of the
exhaust valve tappets. An exhaust valve rotator.
used as a valve spring retainer is installed on the
lower end of the exhaust valve. This valve rotator
known as "Roto Cap", is a spring-loaded bali
bearing device. On each 'lift, or opening stroke of
a valve, the rotator gives the valve a slight positive
clockwise rotation.
The intake valves operate in valve guides in the
cylinder head and are actuated by rocker arms.
The rocker arms are actuated by valve push rods
and the intake valve tappets. The intake valve
springs, the intake valve spring retainers, and the
intake valye . spring retainer locks make up the
remainder of the valve operating parts. An intake
valve spring retainer oil seal virhieh encircles the
upper end of the intake valve between ·the valve
locks and' the tipper end of the valve guide controls
the passage of oil along the valve stem a~d guide.
. . '
No:te:. Whe~- engine. trouble indiCates defective
valves as a possible source -of trouble, also check
the . vacuum-pump-tq~manifold ;vacuum line con~
nector. ·