W-0 DOWN-DRAFT CARBURETERS 539S-698S

Form 4638R U. S. ARMY TRUCK-53<fS.6'18S February, l'l-42

Revised June, 1954

CARTER CARBURETOR

For quick reference, file this pege under "Univar,al Carburetors" in your manual, elthoug h this is not a U niversel e<1rbureter,

MODEL

"MB" 4x4

u. s.

ARMY

TRUCK

Casting No. 407 on face of flange.

W-0 DOWN-DRAFT CARBURETERS 539S-698S

CARBURETER SPEGI-AGA-T-IONS

For MB <4x4 Gove rnment Trud:

Oimen,ions: Flonge size, I in ch S. A. E. Primory venturi, 11 /32 inch I. D. Moin venturi, 1.0 inch I. D.

Roat ?Otting: Distonco from float lat free endJ to float chomber cover to be 1/a inch with free weight of Aoot on needle end spring.

Vents: Outside, No. 10 drill size.

Gasoline lnfo�e: Square vertical !spring loodsd) needle. No. 53 drill size in Mtdlo seat.

Low Speed Jet Tube; Jet sizo 1539$). No. 71 dril". 1698S) No. 69 drill. Idle well jet. No. 61 drill. Sy-p�si :n body, .059 to . . ObO inch diamoto,. Economizer in body .. b425-.0<435 inch diomeleo. Idle bleed, size No. 52 drill.

ldl& Port: Length .. 140 inch. Width, .030 inch.

Idle Port Opening: .081, tci .090 inch obove upper edge of velve with valvo dosed tight.

Idle Screw Seot: No. ◄6 drill. .

Set Idle Adjustment Scrow: I to 2 turns open. For richer mixhm1. tµrn screw out. Do not attempt to ,idle engino bolow 8 miles per hour.

Jl/1 Inch Bore; -4-¾ Inch Stroke

Mein Nonie; !Flush type) in primory venturi, angle 30•. Discharge jet size, .0% inch diameter.

Metering Rod: EconoMy step, .060 inch. topers lo .0+8 inch diometer. Power step ,047 inch diameter. length 3-23/H inches.

Metering Rod Jet: Siu .. 070 inch diameter.

Metering Rod Setting: Use gauge, put No. TI09.2i, (2.718 inches).

Accaleroling Pump; High pressure delayed <1ction type (spring opcro+ed plunger I.Discharge jet site, No. 73 drill. Relief p�ssoge lo outside. size No. +2 drill. lnla�e b<,II ched si10, No. 40 drill, Di,charge disk ch,,ck size, No. ◄0 drill.

Pump Adjustment: 17 /b-4 ir.ch plunger trove! of full throttle position. Uso gauge TI09-l 17S.

Choke Manuel-Offset, butterfly type with poppet volve. Infer· connected to open throttle valve to fast idle position whon choke is used.

Motor Tune-Up-Be Accurate I

CAUTION: Chonge worn or lea�y flan911 gaskets. Tighten manifold bolts and test compression before adjulting carburetor.

Spark Plu9 Gop .030"

Set Breaker Points

.020H

Use Timing Lignt Breaker Point< to

Open al IGN Mork on flywheel

"'1-l(N M010-. 1' AT OPtR.ATl�C HMPUATUU

VA.LY( CJ.lA.AA.N<I

Sci Valves (Cold I

Intel• .016" Exh'a\Jst .0 16"

Floot Setting (Meosure lrom machined

surface of cuting) l/a"

ldlo Adjustment Screw Setting

I to 2 Turns Open

Questions?Call us Toll Free at:1-888-648-4923

(Mon-Fri, 9AM-5PM, EST) or email Mike Meditz at: [email protected]

Po9e 2 ----· - ·-------------------------------------------

SERVICE INSTRUCTIONS

TO DISASSEMBLE Remove carburetor from motor. Uso Corter Tool Kit.

I. Remove chote link pin sprir.g, choke connector link and ,pring. 2. Remove •ir horn assembly, wiih all p•ris attached. 3. Remove idle well plug assembly. 4. Remove idle well jel. 5. Remcve throttle shaft aim and scraw assembly asd H,roitle con•

nedor rod. 6. Remove bowl cover with •ii pods oHoched. 7. Remove pump spring from pump cylinder in body. 8. Remove low speed iet p!ug am,mbly. 9. Remove low speed jet. ·o. Remove idle ediusting screw ond spring. ! I. Remove metering rod jet a«embiy. 12. Remove r.ortle possoge plug os,embly.

t...-,s,,...iJ ..

· 1mu1a1w

�v••

n-iE LOW SPEH> ClRO..U

Fig. I

Fig. 2

D. Group oil pump circuit pods. (Fig. 4.) E. Group all chole system port,. Examine each part in each group and ,.,place those pa,t, that shows sign� o{ weo.r 01 damc\ge. Clean d!I pads in gasoline and blow off wdh compressed air, If ony corbon i, in the bore of fhe flange, remove it by scrophg or with sandpaper (do not use emery cloih). lsscoli o!I parts light.

TO REASSEMBLE Assemble pods in gfoup "A"

26. lnstoll needle seal in bowl cover. lnstoll bowl cover goskot. Then put pin and spring into needle <>nd install ,n soot: then install float end lever assembly.

13. Remove nozzle retoiner p!ug. 14. Remove nozzie or.d nonle gasket, using tool TIO'i"-178. IS. Remove body flange attaching screws ond ihen remove P.onge

27. Set floot level, Turn gosket· around so g�ugc con be piau,d on 1nachined surface of casting. Correct setiing is 18 •. ( Use to<:>i ilO'l-80). Do not depress flooi lip ogoinst spring in needle, buf let floot re,t of its own weight. G•uge ,�ouid then be placod between freo end of float ond machined surfa�e :,f bowl ccver. F!oot should be set so it berely touches gouge. Adiusiment i, ob!oined by bending ti-le lip on floai which con!oc1s pin ;n noadlo. Do not bend on front of float in adiu,ting. a1 damage will 1esult.

from bcdy. 16. Remove strainer passage plug as!embly and strainer. 17. Remove intake ball check assembly. 18. Remove discharge disk ched essembly. 19. Remove pump jet possege plug assembly. 20. R9rnove pump iot. 21. Remove ihrottle volve screws. throttle velvo and throttle shoft

ond lever o,sembly. 22. Removo idle port rivet plug. 23. Remove chcle iube brackel assembly. 24. Remove choke volve sere"''· choke volve ood cnoke shoH ond

lever 4ssemb!y. 25. Disassemble all ports from bowl cover.

Cleen ell costings 1horoughly inside end out wilh o smell brus� ond clean gasoline, or suitable solvent cleonar. Then blow oil passages out wHh compressed oir. Group oil pods os follow,: A. Grcup all par1s controlling the go,olino level. (Fig. 2.) 6. Group all low speed circuit pMh. (Fig. I.) C. Group oil high speed circuit parts. I Fig. 3. I

EARLY PROO UC TION (BRASS TAG MARKED Kl)

The first 4,000 539S carbureters, identified by "Kl" on brass inspection tag, used parts marked,. CD. After the first 4,000 carbureters, parts marked © were used.

Parts marked © are not interchangeable with ports morked ©. Eorly carbureters marked "KI" can be brought up to latest specifications by installing 3-466U for servicing only the throttle ,;haft and lever assembly, or l-4 I 3U for servicing body flange assembly. Necessary ports ond instructions are includedin unit packages.

When serv1c1na loter corbureters, order only parts ;eeded for job. (See Parts List on ooae 4.)

Hool.Po-,.

M•h� P.odJ.t

THI: HfE,f-1 S:P£W CLRCVJT

Fig. 3

LATE P�ODUCTION



-.c.,.,..,.,.�o;j l'Jwvttl• Sha# Affll Oa"'p Sct.v llirot4I• sJ..o.ft � -d Sc:,� A.U)

THE IVW CIRCUIT

Fig. 4

Assemble parts in group "D" 28. lnstoll pump jct end pump jet plug a«embly. 2�. lo,ta!I d;schorge • di,k check ossembly. 10. lnstell intoke boll ched es,embly. 31. Ir.Hall pump check strainer end strainer plug """mbly, 32. IMtatl pump spring. 33. Install pump plunger and r od essembly.

Assemble pclrh in group "'8"

M. ln;tell throttle shef1 or.d lever assembly, bod out throitle lever odiusting sc,ow, then instofl throttle velve end throltlo volve ,crew ( be, ;ure lrod6-mark oo volve is toword the idle port side cl cor\:ureter when viewed from manifold side}, With volve screws loose, toi:, throttle vo Ive lightly to centrolite it in boro of cMbureter, Hold volvo in piece with fingers and securely tighten screws. (New screws are recommended.)

IS. lu,toll idle odju,tment screw ond idle adjustment screw spring. lb. Install idle port rival plug. )I. lnstol! insulate, ancl new go,kcts, fh .,n instoll body on l1onge.

tightening screws evenly end securely. 38. lnst<>II low speed jet. Work jet well into seat by moving bod

and forth, then install low speed jet plug assembly. 3'1. lnstoll idle woll jet and idlo well jet plug assembly.

Assemble porh in group "C" 40. Install metoring rod jet ossembly. 41. Install bowl cover ,., oo�embled. tightening screw, down cvoniy

and �acu'";:e!y. 4?. lnsloll pump orm ond coi!ar and pump operating lover os<embly

.eind spring on pin in bowl cove,. •J. lnstoll pump connedor linl (ends t,wey from bore ond pin spring

ot top). •-1 lnsro!I th,ottlo shoft �rm end screw ossembly on throttlo shoft. 45. lnsloll th,ottlo connector rod in lhrotlle 1h1>ft orm, using spring

ond re ttJin"&r at lower er1d �nd pit. spring ot top end. :.

4c. Pump Adjustmont: !lock o ut throltle lever set scrow. With th,ottie volve seoted, pump �hould trevel 17/M" from closed to wido open t�.rottle. Adjmtment con be mode by bending throttle connecror rod o+ lower ongle wilh tool Tt09-41. Pump trovol con be meosured by using universal pump strole gouge T 109-1175 by p•ocing boso cf gouge on r<,ised porlion of bowl cover so ihot projecting eor of p<1mp gouge rests on top of pump shaft (See Fig. 6). Hold gouge vertiul, The difference between the number shown by index mMl on gouge, ot wide open ond closed �hrottle p<>s:tions, should be 17.

47. Metoring Rod AdjustmQnt: With shoulder on metering rod seoted in metering rod jet. me tering rod pin must bo odjusted lo lightly contoct top of m eforiflg rod eyelet with .01 SH to ,018" opening between edge of throttle valve and bore of corbureter ( side op· posite idle port I. Use gouge T 109-44.

471'1. Optionol Adjustment: (See Fig. 5.) Correct selling of metering rod is importont ond must be mode ofter pump odjustment, I nstoll metering pin ond $pring assembly. w asher and nut loosely on purn0 operating lever. Insert gouge (tool TI09-26) In

Fot-m 4-6:>SR Page 3

pl�ce of metering rod, seoting tapored end in metering rod jot. Hold geuge vcrticol to insure seoting. With throttle volve seeted, push metering rod pin downword until pin res" on sho ulder o/ notch in gouge and tighten nut (tool 1109-761. Remove gouge, ond ins�ell metering ro�. disc end pin spr_ing. Conned metering rod sprin� (end of sp11ng through hole ,n metering rodl.

�S. After adjustment, m et ering rod seots in metering rod jet when thr�ttle is odiu>1ed for norm11I curb idle. Metering rod spring must exen ;light downward pressure of met&ting rod on meter-

flod Nn H•1 Nut•

fig. s

rng r od pin whon off jet. B'lnd lower end of spring do,..nword wher� neces�ery.

49. Install noule and nozzlo g<>,ket, using tool No. TI09-55. Be sure that flat side of noule faee, up.

50. Install noz,le reloiner plug o�d nouio plug osse:nbly.

Assemble parh in group ''E" 51. lnstoll oir horn on body. 52. lnstell choko shoft end lever essembly Md choke pull back spring. 53. Install choke volve, choie volve screw, centrolizing the volvo in

o ir harn. then tighten valve screws. '

Si. !nsloll chol·e operating lever ossembly and hook pull bad spring 1n ploce .

SS. lnstoll choke connector link, connedor lin� spring ond pin ,pring.

OTHER CARBURETER ADJUSTMENTS If carburetor foods up ofter considerable service float level should

be checked, Weor on lip of float lever will roiso float level. floot level moy be rese1 by bonding lip of floot lever down to reise flooi level or bendi ng lever up to lowor floof level. Only o very slight bend i, needed.

If '."otor stoll, while id�ing, _rosot th,otile odjusting screw ond idle odjusrment screw to spec,ficoftons. If those odjustments do not cor• red _the frou�le 11 J Remove idle well plug ond gosket essemb(y, ol low,ng goiolrne rom the bo�I to flush out idle woll iot. Rem ove

,die well 1et ond blow out with com• pressed air. (2J Remove low speed je: and clean thoroughly wi1h compressed oir. Exomino and see the! jet seets gosoline tight at shoulder. If not, replace with a now jot of i dentical ,pscificotions. {3 J Examine bore of corburater eround thro!tle volve for car

bon occumulotion.

Fig. 6

A clogged pump jot should be removed and cleonod with compr essed oir, which, in mony c<>ses, will remove the dirt or lint. Howover, it is usually ed,isoble to reploco the pump jet, e, its cost is nominel. All jeh end cheeks must be seoted go,olino tight.

Poor occel erotion mey bo due to d<>m<>ged or worn plunger leotho, in accelerating pump, loose plung&r, cor• rosion or sediment in pump cylinder or bent pump orm (pa rts which may be roplacad et smoll co st).



@' It j � 118.)& 118.-11 IJB.79 UB-105

'ii' � rg w g , , 118. 108 118-1255 118.127S 118.129 5 DB-16-4 12·255 12.m

1-◄IZS

�14•246S 7P 2�? �• .:45 20. &1 20.71 21.14S )0.20 l0A.]9

1 39.10 39.11

p y ◄].67 "9.84

@ � l5)A.JUS S]A.251S .

i , 1 0 @ 1 " NOTE: Pa.-l$ are showu here for identifio;,t.lion only. Ched< o;on-ect nUJnber and price in parts list. � � �

61•57 61·119 61·)28 1,J.143 6t.J69 41.l?J 6l•l'J0 61·20? 6l• 272 1o.---------------.1

i n.13-1 6).93 6◄·62S 75.547

�

75.541

86·10 Bb-11 B6·1S 1

10�10 101.2s ,01. 120 IOl•l-42S 101. tSOS

ff t 121•◄75 171-6-4S

l101.,eJS

0 129•1S l◄b- 95S

U. S. Army Truck Carbureters 539S.698S

@J co ,;;;,

IOSA.J) JOSA·l� 114.21S

=

150.97 150- 98 IS0A.10 18J.J9

W H EN S E R V I C I NG, USE GASK E T ASSORT M E N T No. 175A; R E P A I R PAC KAG E No. 1319B

P A RT NAM ES I N C A P I TAL LETTE RS, LIST E D BELOW, I N DI CAT E CO N T E NTS O F R E PA I R PACKAGE

Part N o. 1 .4oas

1 . 412s 1 •419U

1A•55S

2·89 3•463S

9-465$ 3 ·466U

s.312s 7.1 165 1 1 . 180S

1 1 - 1 86S 1 15 .35 1 1 5.41 1 1 5.79 1 1 B-1051 1 B-10S 1 1B-125S 1 1 B - 1 27S

1 1 B•129S

l 1 8·164 1 2-2551 2-323 1 4.246S 20-2220-2620-45 20-61 20.12 21 -74S 24-2325.935 30-2030A·39 39-10

39-11

43-67 48-846SA·168S 63A-251S 61 -57 61 -11961 -12861 -143 61·169 61 •171 61 -190 61 .207 6 1 - 272

P A RT N A M E (DBody flange assembly (early productlon)

(539S) (Sup. by 1-USU) @Body fl::mge assembly ••• ·-······-···---·····-··········-·

Body llange a�embly. metering rod and lube clamp unlt (for servicing early nroducllon) (539S) ········-···--··········-···-········-···-··-·--······-·-

FL�"IGE GASKET AND DIFFUSER ASSEMBLY ··--•··-········---·-·-·--···-···--··

Throttle valve ··-·-···--·-···-···-·--·-···-···-·-·--·-©Throttle shaft nnd lever assembly (early

production) (539S) ····-···-·····- ·····-·-··· .. -··-········ @Throttle shaft and lever ll.:lsembly .•. --············

Throttle shat! aasembly, metering rod nndtube cla.mp unit (lor servicing early production) (5i9S) ·-······---···-· .. --.••.•.•. ·····--·

Air horn assemblY····--·-··-···· ··--·-················--·· Choke valve assombly •• ·--······-·····-···· .. -················ Low gpeed Jet assembly (539S) (Sup. by

11·186S) ····-···-·-········-····---··-·--·-···-··-···-·-··-LOW SPEED JET ASSEMBLY ..... . .... .. . .. .... ... .. .. . RIVET PLUG ····-···········--··---·-·---···········-····Rlvet plug ···· ········-···-··-·-··· ···--·--·············· ······· ···· RJVET PLUG ···-·····-················-···-···-········-····<S) Nozzle retainer -plug (539S) ..-···-···-···-···-·········�· lDLE PORT RIVET PLUG.·--······-······-·-··-····· STRAINER PLUG ASSEMBLY ... ·-•··· · · · ······ ····· ··· NOZZLE AND PUMP PASSAGE PLUG

ASSEMBLY .-................... -... .. ..... ..... .. .. .......... .. . (2) LOW SPEED .JET AND IDLE PASSAGE

PLUG ASSEMBLY ····-·--·-----··--<2) NOZZLE RETAlNER PLUG (698Sl-.. -·---··· NOZZLE (539S) --········-······ ······-............ _ •.••. _ .•.•• --. NOZZLE (698S) -··-··········· ............ -·-·······-······· .. ·-··· Choke control lever and shaft assembly ........... . Needle seat and plug gasket.·-···--·····-· ........ (3)Metering rod Jet and plug gaskct--····· ·· ·-···<3)NOZZLE GASKET (698S>-···--···-· .. ····· ......... --Stra lncr plug gasket··· ·-·--···----·····-· · ··--.... . _ .... NOZZLE GASKET (539S) •••• ·-······-······· ·····-.. ·-······ Float and lever s.ssembly ........ _ ........ -······-·····-·····Float lever pin ••..•• ············-·-·····-··-·-.. -··-·· .... • .. ••• ..NEEDLE. SPRING AND SE.AT ASSEMBLY PUMP CHECK STRAlNER. ... --... -.. -······-·····-····· Idle adjustment screw ..... , ............ ................ . .. .. .... ... . CHOKE VALVE ATTACHING

SCREW -· .. ·--······~······--·······--·-········ ····· ······• ..... (2) THROTTLE VALVE ATTACHING

SCREW -··-------· ·············· .... ············ ·-·· -······· ·· ·-·· •• (2) IDLE WELL JET •••• ·-········-.. ·--·--··-···-···--········ PUMP JET ............... ......................... •·······-····-············ Pump arm and collar a.ssemblY····-·---··········-Pump operating lever assembly ........ _ ........... ·-··· Idle adjustment screw spring ..... ............ ..... .... .. ... . CHOKE PULL �A.CK SPRING ............. _ ........... . Connector rod spring (Use with 115-59)_ ....... .Plunger S!lT lng ··"�·········-···-.. ·-.. ·-·-·-················-···· PUMP ARM SPRING ••• ·---·········· . . ···-············---· · PUMP SPRING ......................... -............................. . CONNECTOR LINK SPRING ...... ·-····•······-···-··· .. . [nlake needle spring ................................................... . METERING ROD SPRING ........ ·-···················-·····

(D and © See Instructions and lll ustratlons at bottom or page 2.

Part No, 62- 108S

62- 131S

62·134 62.135S 53.35 63.93 64•62S

75.547

75-548 86. 10

86 ·11

ss.1s 101 . 10101-28101 -82

101 -120 1 01 - 121

101 -122

101 - 142S

101 -150S

101 - 1 83S 101 -184S

105.11

105.13 105A-8 105A•13 105A .19 114·21S

115.59 115- 142 117-58117-106 120 - 1 5 1 S121 . ss 121 -73 122•47S

122-64S129 - 15135 . 39 146- 95S 150.97 150.98 150A . 1 0 172•21 1 83.19

PART NAM E (DChoke tube bracket assembly (early

production) (539S) -·-····· .. -········ ................. -.. .. (DTube clamp assembly (early production)

(639S) ·--· .. -·-···--···-·-··· .. ·······-···-··-· .... -•••• @Tube clamp ........................ -........ --···---···-· .. ··-·

. @Choke tube bracl,et assembly ........... _ ............... . Spring :ratalnor (Use with ll6•S9) (689S>.-···-

�f-lJ:._forJrl��D

( ��Dw�is��y(69SS)._ •• _(Identity by shaft No. �9·121) ..•.•. -········-···-·····

METERING ROD-STAND.A.RD-.060'' to .0iS"•.047" ----···-··--·-···· .. ·-·············-··-·····

.Metering rod-l size lean-.06075"•.0486".--Bowl cover lock washer (Use with

101 •82) •••••• .......................... •-•••-H•••-••w-.. ,( 4) B

�gi-f2"t,g

�-�.�.�'._:�:�.�:._!�_::�-:�:_h ..... -.. ·-····(2)

Flange stud lock washer .. ·-·--·-········ .. -·--·<2)Wire clamp screw •••.••••• -·-··· .. ···-·· .. -··-··-··········· .. •••• Throttle shaft arm clamp screw_ ...... -..... ..... . }low! cover attaching screw (Sup. by

101·184S) _ ........... -----·--··-···--····-··-··-Throttle lever adjustment ,;crew ........... _ ............. .Throttle lever adjustment screw (Sup. by

101· 120) ·······-··---.. --.--..... .. _ ...................... .. ....... . Body flange attaching screw (Sup. by

101 • 183S) ..... ......................... ....... ·-··-·········- ... .... ....... . Choke tube bracket screw and washer

a..sembly ··-·····- ···-···-······--··· .. -···-··-· ·-·-·-·· · ······ · AIR HORN" SCREW AND WASHER Bt�i

E�f-JriE

-·ATTA.CHIN<f

·scREW-

··<2)

BS°� "'s'tJJJl� ,t.n_f?:fl!Jc! sc'iIBw·--<2>

AND WASHER ASSEMBLY_ ......... _ ...... ___ (4) (DTube clamp screw (early production)

(539S) ········--··-·-···-···-··-··-···-·· ················-··<2) Tube damp screw---····· ············ ············· .. -• .... _ ..... _ .... . Tubt0 clamp n ut (late production l; early 2) ... .F1ane-e nut .......... __ .......... _·-······· -·-.................... _ .. (2) METERING ROD PIN HEX NUT ..................... . THROTTLE SHAFT .ARM AND SCREW

ASSEMBLY ····--.. ···----•· .......................... -.. -. Throttle connector rocI (Sup. by 115-142) ...... . TBROTTI,E CONNECTOR ROD ........ _ ......... -... . CONNECTOR LINK ... ... -·-······--· .... __ ..........•.... Choke link ·-········ ............ _ .... ......... _._ ................. _ .. METER1NG ROD JET ASSEMBLY .... _ ........... . BODY FLANGE GASKET .•. ·-··-········-···-·-··-·<2) BOWL COVER GASKET .............•. •·····--·· .. ----···· ... DISCHARGE DISK CHECK PLUG

ASSEMBLY ···· ····-··--········ ····· ·· --····· · ........... _ . . _ •......• INTAKE BALL CHECK PLUG ASSEMBLY METERING ROD DISK. ........... -···········--............. . METERlNG ROD PIN WASHER--............... . Bowl cover and pin assembly ....................... _ ..... . METERJNG ROD PJN ... ----··· .. -·····-··-············ Intake needle pin-··-··········--........... _ ...... __ .. _ ... . PIN SPRING -··········--······ •·•······························· (i) THROTTLE CONNECTOR ROD RETAINER

(Use -..ith 115•142) ....................... _ ...... ........ -...... . Insulator --···· .. ••••••••• .. ••••••• .. •••••••••• .. •••• .. ··········--···-·····

NOTE : Fiou res In parenth�s I ndicate num ber of pieces used in one carbureter. Where no figure is shown, only one I$ used.



Documents

W-0 DOWN-DRAFT CARBURETERS 539S-698S