0300-46
LVILI.YS hlODEL
"MB"
%-TON
4
x
4
GOVERNMENT
TRUCK
If
tlie c;irliiiretor bore
is
restricted witli carboii
dcp<)sit it wil1 I>e iieccssary to open tlie tlirottle
wiqlcr tliaii tlic spccili<!d cipciiiiig to obtaiti tlie
~lroper idle speed. Ol>ciiirig tlie tlirottle inore
tliaii tlie specified aiiioirnt in order to obtaili tlie
proper idle wil1 tlieii iiricover more of tlie slotted
idle port tliaii was iiitctided. Tliis wil1 result in
le;ivitig an iiisiillicient nniount of tlie idle port as
a reserve to cover tlie
pcriod betweeii idle aiid
20
iiiiles per Iioiir. wliere tlie Iiigli speet1 system Iie-
giris to cut in.
I\
Ilnt spot on acceleration wil1
resiilt. Clcaii I>y scrapiiig or witli eniery clotli.
Iligli Speed Circuit
It is rarely iiecessary to remove Llie inain iioazle
No.
20,
Fig.
5.
It cari usiially
11e
cleaned by re-
nioviiig plug aiid blowiiip: out witli compressed air.
If it is daiiiagcd ancl rcqiiires replacing make sure,
upuil installatioii. only olie gaskct is between noazle
aiid its sent
iii
tlie casting.
If tlie carbtiretor lias I>eeri in service lor
a
loiig
titiie or Iias bceii taiiiliere<l witli, it niay be found
tlie
tneteriiig rod is iiiiproperly adjusted or worii.
A
worri ineteriiig rwl will have tlie effect of a ricli
mixture ahuve
20
niilcs lier Iiour. If the meteririg
rod
is
worii.
tlir
iiietcriiig rod jet wil1 also be worn
aiid
botli slioiild bc rc1)laced.
'I'o
adjiist iiietciiiig I<K~, back out tlirottle lever
adjiisting
screw.
"C"
Fig.
9.
aiid close tlirottle
tiglit. Using gauge
'1'-10!l-26.
loosen nut."D" Fig.
9.
arid rnove
11iti
iintil it scats in iiotch of gai1p:e.
'l'i~literi ~iut sc<:iirely.
I<ciriove gauge and iiistall
nicteririg rod,
(list,
aiiil cr>iiriect spring tlirougli Iiole
i11
nirteriii~ rn~l.
FIG. O-METICRING ROD CAUGING
Accelerntiiig
Pump
Circuit
If
tbe punil~ plunger is worn, sticks, or tlie spring
iin<ler tlie lcatlier Iias lost its tension, replace the
pluriger asseriibly No.
5,
Fig.
1.
I1 tlie Accelerator Pump Intake Valve (ball
clieck) No.
29,
Fig.
G
leaks, part of tlie punip dis-
cliarge wil1 be lorced I~ack througli the valve into
tlie float
IIOIV~, tlierel>y causiiig an insuficient
amouiit of fuel to be discharged from the Jet No.
33.
If the valve cannot be cleaned witli compressed
air. it must be replaced.
If
tlie Accelerator Pump Discliarge Valve (Disc
clieck) No.
30
leaks. air wil1 bedrawn into the pump
cyliiicler on tlie upstroke of tlie plunger. This gives
an iiisuficient charge
of
fuel into tlie throat of
tlie carburetor
iipon acceleration causing a flat
spot.
I1 tlie valve caiiiiot be cleaned witli coin-
pressed air so that it works properly.
it
must be
replaced.
I1 tlie Accelerating i'iimp Arm Spring No.
35
is
weak or darnaged. it
wil1 cause poor acceleration.
If the Iiole in the Accelerating Punip Jet No.
33
is too large. the acceleratirig cliarge wil1 be allowed
to pass too last and wil1 make the mixture too
ricli. An erilarged jet iiiust be replaced. A jet
loose
on its $ent gives tlie same eliect. A clogged
jet wil1 result in
a
stuiiible on acceleration.
To adjust tlie puin11 stroke. the pump gauge
'I'-109-117s
sliould be iised. First back out tlie
tlirottle
adjusting screw
"C",
Fig.
9,
so that it
docs iiot toucli the castiiig. In gaiiging the pump
stroke, place the gauge on top of tlie bowl cover.
opeii the throttle wicle tlien ineasiire to tbe top of
tlie pump rml. Close tlirottle tiglit anti measure
again. 'ïhe difference slioiild be
'74''.
To adjust
tlie stroke, bend the tlirottle connector rod at
"A"
Fig.
10.
ALWAYS
SET THE PUMP BEFORE
SETTING
TIIE METERING
ROD.
If set
afterwards tlie
metering rod wil1 be tlirown out of
adjiistnierit.
Tlirottle Coiinector Rod and Throttle Cliaft
Ariii Assemlily may be worn, and allow tlie throttle
valve to be
opeiied by tlie accelerator peda1 belore
tlie pump jet begins to
discliarge gasoline, result-
irig in a flat spot. Replnce al1 worn parts, because
tlie operatioii of the iiieteiiiig rod is also affected.
FIG. 10-PUMP
TRAVEL
GAUGING
To Next Page
Loading...
