c AIRCRAFT CARBURETOR SERVICE MANUAL MODELS MA3A …

1 TheUnitedStatesofAmerica.~JnIl/IONAIRMOT IVECORPORATION()CARBURETORPUMPDISCHARGE{ ;HECKVALVECARBURETORPUMPDISCHARGECHECKVA LVESPRINGCACCELERATINGPUMPLEVERACCELERAT INGPUMPLINKCARBURETORPUMPDISCHARGECHECKV ALVEASS'YHOLE2-MEDIUMHOLE'-MINIMUMHOLE3- MAX(NORMAL)THROTTLESHAFTTHROTTLESTOP~CRE WIDLENEEDLESEATIDLEEMULSIONCHANNELIDLEAD JUSTINGNEEDLEIDLEAIRVENT\THROTTLEBODY& SEATLEVERRETAININGNUTFUELINLETSCREENASS' yMIXTURECONTROLLEVERTHROTTLESTOPECONOMIZ ERCHANNELECONOMIZERHOLEATMOSPHERICBOWLVE NTIDLEAIRVENTMIXTUREMETERINGVALVEASS'YMI XTUREMETERINGVALVEBOWLDRAINPLUGFLOATASS' YMIXTUREMETERINGSLEEVEFIG.}

2 DMODELMA4 SPA~ 'uAATIONACCELERATINGPUMPCHAMBERACCELERAT INGPUMPPLUNGERPUMPINLETSCREENPUMPINLETCH ECKVALVECARBURETORPUMPDISCHARGECHECKVALV EASS'YTHROTTLEFLYIDLENEEDLEDELIVERYFIRST FLYHOLEDELIVERYSECONDFLYHOLEDELIVERYTHIR DFLYHOLEDELIVERYTHROTTLEFLYCLOSEDVENTURI MIXINGCHAMBER& "i-rCONTENTSPAGESPECIALTOOLS4 DISASSEMBLYPROCEDURE5 THROTTLEBODYDISASSEMBLY5 FUELBOWLDISASSEMBLY6 CLEANINGANDINSPECTION7 EXPLODEDVIEWOFCARBURETOR8 AND9,..THROTTLEBODYASSEMBLYPROCEDURE10 FUELBOWLASSEMBLY14"-ACCELERATORDISCHARGE TUBEASSEMBLY15 THROTTLEBODYANDBOWLASSEMBLY16 INSTALLATIONOFWARNINGLABEL:16 TESTPROCEDURE16 FLOATVALVEANDSEATTEST.

3 16 PRESERVATIVETREATMENT17 TORQUESPECIFICATIONS17c-3-NOTEM odelsMA3A,MA3PA,MA3 SPA, ( )~SPECIALTOOLS~I1~I2-~~I4~~I5~na;I313-~~ .8Ai,.~. !NOMENCLATURE---4-rT"jy"vI67910 IwIIREFPART1112 NONO1M-7 Nozzlewrench1/2inch( ) (Notshown, ) ,STANDARDMA3 & 4 DISASSEMBLYPROCEDURE-:Referto explodedview,pages8 &9 )Separatethethrottlebodyandbowlbybending tabwashers(1) (2). softfacedhammertoloosenandpullcastingsap art, )Removefloatshaftcotterpin(3),shaft(4),f loat(5),retractionclip(6),andfloatvalve( 7).Discardbowlgasket(8).2)4).CHANDLE/'"' .5"----"')../FIGURE15)6)7)8)9)10)11)12)1 3)14)15)16) (9),pumplink(10),andpumpplungerassembly( 11).

4 Noteholelocationofpumplinkin pumplever(13).Removeacceleratorpumplever screw(12),lever(13),andthrottleopeningsp ring(14).Removepumppackingwasher(15)andp umppacking(16)witha (17),andsafetywasher(18).Removemixtureco ntrollever(19),lockwireloop(20),spring(2 1),thrustwasher(22),andpacking(23).Remov emixturecontrolvalve(24),horseshoewasher (25),andgasket(26).Removefloatvalveseat( 27)andgasket(28)usingtoolM-104ora (29),nut(30),andlever(31).Removethrottle valvescrews(32),valve(33)andthrottleshaf t(34)..Removethrottleadjustingscrew(35), andspring(36).Removeidleadjustingneedle( 37),spring(38),andretainer(39).

5 NOTE:somemodelsdonotuseretainer(39). (43)seldomneedsservice,howeverifjnecessa ry,pressouttheventurifromthethrottlevalv esideusingtool, '..,-5-FIGURE217)Removethrottleshaftbush ings(44) (45)if used,ventscreen(42)if used,andidledrillplug(66) :Heatingmayeaseremovalofidledrillplug.,I f leadballis usedinplaceofidledrillplug, )"THROTTLESHAFTBUSHINGREMOVERFIGURE3 THROTTLESHAFTBUSHINGREMOVER)./FIGURE4 Removefuelinletstrainerassembly(46)andga sket(47).Removefloatbracketscrews(63),an dbracket(64).FUELBOWLDISASSEMBLY20)Remov eidletube(48)anddrainplug(49).21)Removen ozzle(50),safetywasher(51),andnozzlegas, ket(52).

6 :Occasionallythenozzlegasketwillstayin thecastingwhennozzleis (53),safetywasher(54),andgasket(55).NOTE :Donotdisassemblethepumpdischargevalve(5 3).Removepumpinletretainerscrews(56),saf etywashers(57),retainerflange(58),strain erhousing(59),gasket(60),screen(61),andi nletcheckvalveassembly(62).Pumpdischarge tube(Figure5) it is damagedorloosepullit carefullY' )22)23)1)NOZZLEWRENCH'-'"SOCKETEXTENSION HANDLE'''''\FIGURE5~..ICLEANINGANDINSPEC TIONCC leaningProcess24)Usea recommendedcarburetorcleanerandthecleane rmanufacturer'sprocedureto soak,,rinse, ,channels, )IMPORTANT:Donotcleanpassagesincastil)gs orcalibratedparts(nozzle,idletube,etc.

7 ,carburetorcleaner,anda small, 'ANDMA-4 SPACARBURETORScTABLEII nspection26)27)-7-Thefollowingpartsshoul dalwaysbereplacedduringcarburetoroverhau l:AllgasketsSealsandpacking,Throttleshaf tbushingsRetainersFloatvalveandseatassem blyAcceleratorpumpFloatshaftNOTE:Fuelinl etstrainerassemblyshouldbereplacedif thestrainerscreenis ,cracks,warping,ordamageare,ofcourse, is alsojustcauseforrejection: ,causingdifferentwearcharacteristicsin , '".215T-BodyAc"",I,,, ,lv.(Bottom). ' , ", ", . "'PNECJBJDNAIRMOTIVECORPORATION@~NOTE:Th isillustrationdoesnotdepicta @II!@i'@@Iii@IIIII@~@ ,JII/to//-;//I~'"'"~,~",~.

8 /,::,ry."',';J,~-,T~"'~"'j;t~~;~~~"~,~,/ ,L~:FF:;~~~;,,:~~'/;?/fi,;,'..'-"-~- ".",J" .ALVE':-~,h~233-615 FLOATV--'-,;, ;'.>-III)!~/I.)t9JI/~@V@~"'~"1@Il~------ ------------I@/ & 4 ASSEMBLYPROCEDURETHROTTLEBODY28)Lightlyc oatthebushingwithLoctiteRC-680perLoctite ' (44) ) thiscasethattheloosebushingsarein ).31)-10-Installpumpstempacking(16)andre tainer(15) placeonthe~bottomsideof throttlebody;slippacking(t 6)..In (15)overpackingandstakein (43) thesideoftheventuriwillbeinalignmentwith thenozzleandthelegsengagedin thegroovesinthethrottlebore.')./.~THROTT LESHAFTBUSHING~REAMERTAPWRENCH/.

9 /) )32)Installtheeconomizerjet(45)if ,soasnottodamageorburrthisjetsincethisca ncausea changein (42)if used.'Installidledrillplug(66) (34),throttlevalve(33),andthrottlevalves crews(32).Runscrewslightlyintoplace,rota tetheshafttotheclosedpositionandtaptheva lvelightlywiththescrewdriverbladetoseatt hevalvein ~ (32) ,lIed, :Certaincarburetorsdonotusea wideopenvalveandyoumaynoticethatthevalve is ,adjustingscrew(35),andspring(36)..Insta llretainer(39),spring(38),andidleneedle( 37).Approximatesetting1-1 :Somemodelsdonotuseretainer(39). (25)in itsgrooveonmixturecontrol)lalve(24).'Pla cewasher(26) (23), washer (22),andspring(21) thelockwireloop(20)intoitsholein (19)withwireloopandpushdowntocompressspr ing(21).

10 Assurethattheloopofthelockwireis (17)throughsafetywasher(18),lever(19)and lockwire(20) ,33)34).35)36)37)38)39)41)42)43)44)Insta llfloatbracket(64)withscrews(63)torqueto :Screw(63)shouldbereplacedif (14)(ifused)overtheendofshaft.(34)andins erttheendthroughtheholein (13)andsecureinplacewithscrew(12).Torque screw(12) (12) modeldoesno~ (12).Placethrottlelever(31)atproperangle locationonthrottleshaftandsecurewithreta iningnut(30).Torquenut(30) :Carburetorwithoutthethrottleleverlocknu tretainingfeatureontheendofthethrottlesh aftmusthavethethrottleleversafetywiredas shownin (11)carefullythroughthepackingandinstall pumplink(10)andcotterpins(9).