0100-24
\VII.LYS
hlODEL "MB"
K-TON
4
x
4
GOVERNhlENT TRUCK
VAI-VE TI
hl
ING
'L'o set tlie valve timing turn tlie cranksliaft
co
No.
1
and
No.
4 pistons are at top dead center.
Place camshaft sprocket on camsliaft. turii caiii-
cliaft so punch mark faccs piincli inark on crank-
sliaft sprocket.
Iteriiove sprocket and place tlie tiiiiing cliaiii oii.
tlien place timing chain over crankshaft sprocket.
cliangiiig
position of camshaft sprncket within
cliain until the cap screw Iioles in sprocket aiid caiii-
slinft are in liiie.
Tiniing is correct wlien a line ~Irawii between
sprocket centers cuts tlirougli timing marks oii
--
botli sprockets. See Fig. 14.
Inlet opens
9'
before top center measurml on
flywlieel or
,039" pistori travel from top center.
To
check valve timing. Fig. 13 adjiist inlet valve
.
tappet No.
1
cylinder to .020t'. Kotate crankshaft
clockwise until piston in No.
1
cylinder is ready for
tlie intake stroke. at wliicli time the tappet shoiild
just be tiglit against end of valve stem and mark
on
flynlieel
"I
O"
is
in center of timing hole
iri
--
--
flywlieel Iiousing, see Fig.
l;.
-
--
--
TIMING CIIAIN
COVER
AND
SEAL
FIG. 15-TlhllNG
MARKS
(FLYWHEEL)
The tiniiiig cliain cover
is
a pressed steel ctaniping
Iieavily ribbed lor strength.
The statioiiary pin in cover is so located
as
tn
benr
:igaiiist tlie pltinger in thc crid of canisliaft
whicli coritrols tlie end play of camsliaft.
Tlie cranksliaft
oil seal is woven asl~estos impreg-
nated with grapliite and oil. When necessary to
install new oil seal, tlie steel retainer slioul(l also
be
renewe~l.
FIG. 14-Tlhllh'G SPROCKETS
Crankahaft
Tlie cranksliaft Fig. 16 is of drop
forged steel,
grain direction
following sliape of cranksliaft with
tour integral counterweiglits. Tliis short shaft is
rugged and reduces torsioiial vibration, weight 41%
Ibs. After machining, tlie cranksliaft is balanced
statically and dynamically, aiid
tlien dynamically
balanced with clutch and flywlieel as an assembly.
It
rotates on three steel back babbitt lined bear-
ings, tlie front bearing taking tlie thrust. The
packing at the
rear bearing prevents oil getting
into
clutcli and los when parked on steep inclines.
The main bearing journal diameter and length
dimensions are as
follows:
Fron t-2.3340''-1.920"
Center-2.3340"-1~~o"
Rear-2.3340"-1w
The steel back babbitt lined bearings are made
to
size and are interchangeable without line ream-
ing. The running
tolerante
of the bearing is
establislied at .OOlf'. No adjustment is provided
on tlie
main bearings. Sliould tliey require atten-
tion they sliould be replaced to maintain proper
control of oil. Main beariiig cap screw torque
wrench reading 65-70 ft. Ibs.
Tlie end play of tlie crankshaft is
.004" to .008"
and adjusted by sliims between the crankshaft
sprocket tlirust
washer aiid end of Main Bearing,
Fig.
17.
To adjust end play the crankshaft sprocket must
be removed with
gear puller, Fig.
18.
Whenever
it
is necessary to remove the crank-
shaft or install new cranksliaft bearings. tht engine
lias to
be
rcmoved from tlie frame. See Note under
"Fl~?ïheel" Pace 32.
-,
~~
"
Undersize main bearings are available in .OIO":
,020" and .0301'.
To Next Page
Loading...
