Mercury 1955-65 4 Cylinder Manual - Cal
Contents
1. Fig M7 31 Before disassembling the direct drive lower unit check to see if it is Standard Rotation A or Counter Rota tion B through forward gear to hold it in position then check the backlash Adjust to 0 003 0 005 by adding or removing shims 12 Adjust mesh position by means of shims 19 Shims are available in thicknesses of 0 002 0 003 0 005 and 0 010 When adjustment is complete reassemble by reversing the disassembly then measure backlash of the reverse gear Adjust to 0 003 0 005 by means of shims 24 Fig M7 29 or 31 Fig M7 30 NOTE Adding shims in four cylinder models will IN CREASE backlash On six cylinder units add sufficient quantity and thickness of shims 16 Fig M7 30 to bring the assembled height flush with seating surface of water pump base 48 This measurement can best be deter mined by installing additional shims then measuring the resulting gap with a feeler gag Direct Drive Types Direct drive type lower units have no shifting mechanism or clutches The direction of travel is reversed by reversing direction of rotation of the engine On late models the propeller shaft may rotate in either the standard counter clockwise direction as shown in view A Fig M7 31 or clockwise as in the counter rotation unit shown in view B Refer to Fig M7 31 to determine the type of unit being serviced QUICKSILVER UNIT Refer to Fig M7 32 The water pump is house2. and may be refinished on a lapping plate after re moving reed stops reed valves and dowels Do not attempt to bend or straighten a reed petal to modify performance or to salvage a damaged reed Never install a bent reed Lubricate the reed valve units with Quick silver Multipurpose Lubricant or a light distributor cam grease when reassembling Each reed valve unit has eight reeds which are right hand and left hand units and are available only as a matched set When installing reed valves place the reed petal with the cut out notch N to the left as shown Crankshaft must be removed be fore reed valve units can be serviced FUEL PUMP Diaphragm type fuel pumps are used Two fuel pumps are used on six cylinder models Pressure and vacuum pul sations from the crankcases alternate to pull fuel from the supply tank and supply the carburetor Most of the work is performed by the main supply chamber 5 Fig M7 17 Vacuum in the crankcase pulls the dia phragm 2 downward causing fuel to be drawn through inlet line 8 past inlet check valve 7 into main pump chamber 5 The alternate pressure forces diaphragm out and fuel leaves the chamber through outlet check valve 6 The booster pump chamber 3 serves to dampen the action of the larger main pump chamber 5 and increase the maximum potential fuel flow OLD OUTBOARD MOTOR When overhauling the fuel pump use Fig M7 18 as a guide All defective or ques t
3. until the piston strikes gage then thread gage out until crankpin will pass over center while in contact with gage plunger Rotate flywheel counter clockwise then without moving threaded outer gage body depress center plunger and turn plunger 4 turn Rotate flywheel clockwise until piston crown strikes the plunger Attach one lead of a timing test light to the No 1 Coil Primary White Lead of Terminal Block and ground the other lest lead Retard the distributor clockwise until test bulb lights then move to the ad vance direction counter clockwise until test bulb just goes out With intermediate timing position deter mined move pickup plate 2 Fig M7 11 until tab 3 just touches the cluster finger 4 and tighten the attaching screws Again move the speed control lever until distrib utor pilot just touches the maximum advance stop screw then bend the nylon covered pickup pin 5 until 0 000 0 015 clearance exists between pickup finger 5 and cluster finger 6 To synchronize the reverse throttle pro ceed as follows On Merc 600 and 700 make sure that throttle valves are closed then loosen clamp screw 1 Fig M 712 and position re verse pickup finger 2 so that leading edge is approximately inch in front of carbu retor float bowl as shown Loosen the screws attaching the reverse pickup stop to the distributor sector goar and adjust the reverse timing until points break at 0 030 inches before Top
4. 69 SO 0a g a Thrust hub Cupped washer Propeller 58 Bearing carrier 59 Ol seal 65 60 Oll seal 66 61 Washer 47 Splined washer 62 Gearcase cover 68 Tab washer 63 Thrust washer i Propeller nut view of lower unit gearcase and associated parts used on six cylinder full gear shift models applying slight pressure on shift plunger while cross pin is removed To disassemble the drive shaft the water pump must first be removed On four cylin der models remcve the water pump cover 30 Fig M7 29 using Mercury tool 91 22119 or a suitable spanner wrench Lift off tho outlet plate 31 then remove impeller 32 by prying it out with two screwdrivers Re move the impeller drive pin 33 Removal of the water pump cartridge 35 requires the use of Mercury Cartridge Removal Tool 91 22118Al or equivalent to pull the cartridge On six cylinder models disassemble pump as removed using Fig M101 as a guide The flushing plug must be removed from plug hole P before pump base 48 can be withdrawn To remove the drive shaft remove the retaining screw 21 Fig M7 29 or nut 23 Fig M7 30 Clamp the drive shaft in a pro tected vise and tap the housing downward with a soft mallet Remove and save the shim pack 41 Fig M7 29 or 19 Fig M7 30 located under the drive shaft ball bearing These shims control the mesh position of drive pinion On six cylinder motors shims 19 Fiq M7 30 are i
5. Dead Center of the piston Mercury Four amp Six Cylinder 1955 1965 Fig M7 12 Reverse pickup finger adjust ment used on some models Refer to text 1 Clamp screw 2 Reverse pickup finger ONY Fig M7 13 Reverse throttle pickup adjust ment used on Merc 800 1 Pickup stop 2 Pickup finger 3 Drill gage NOTE Proceed as previously outlined for determining intermediate advance except rotate flywheel clockwise from top dead cenfer then counter clockwise to the ad vance REVERSE position Move distributor COUNTER CLOCKWISE until test bulb lights then CLOCKWISE to the timing position When intermediate timing position has been determined move the reverse pickup stop to just contact reverse finger 2 and tighten the attaching screws On Merc 800 direct reversing motors refer to Fig M7 13 The reverse pickup lever 1 should be moved to the end of slot away from pickup finger 2 and the retaining screw tightened and safety wired If cor rectly adjusted this lever should not be moved Move the speed control lever to ward Fast reverse direction until dis tributor contacts the maximum reverse stop Loosen the screw which clamps the reverse pickup lever to throttle shaft Man ually open the carburetor throttle until a No 40 0 098 drill bit cam be inserted be tween throttle valve and port side of car buretor barrel as shown at 3 With drill bit olding throttle valve open move the picku
6. k Fig M7 8 Cluster lever 3 must be ad justed on throttle shaft on some early models Refer to text Clearance eet screw Cluster finger No 1 pickup pin wr STEN m Ly A ec DI gt Fig M7 9 Latch spring adjustment is re quired on some early models A Adjusting screw L Latch P Sector pln attaching screws Move the speed control lever to Fast position and adjust the full throttle stop screw 4 to allow throttle lever 1 1 64 inch travel to full open throttle position Move speed control lever fully to Slow position and adjust the idle limiter screw opposite full throttle stop screw 4 until the recommended slow idle speed of 525 rpm is obtained Mark 75 75A 78 and 78A First make certain that the distributor is properly timed and adjusted On Mark 75 and 75A fully retard the throttle and with throttle valve closed loosen the set screw S Fig M7 8 in throttle valve cluster 3 Move the clus ter 3 on throttle valve shaft until a clear ance A of 2s Inch exists between pickup finger and No 1 pickup pin 5 On later motors the cluster is automatically posi tioned by the set screw On all models slowly move the speed control lever in the forward position en gine not running until the magneto advance stop just touches the crankcase Refer to Fig M7 7 Loosen the screws securing the throttle actuator assembly 1 to sector gear then move the
7. of points and completing a separate ignition system for three of the motor s six cylinders The contact points must be adjusted to 90 dwell period and a 60 alternate opening position using the Mercury Distributor Point Dwell and Synchronizing Plate C 91 45510A1 or a distributor stroboscope To install the distributor drive belt re move the distributor pulley flange plate 15 Fig M7 21 then remove the flywheel us ing a puller Turn the distributor pulley until SERVICE MANUAL Fig M7 19 Recommended timing gage showing adjusting position left and ad vance timing position right Refer to text Fig M7 20 When timing the magneto or distributor or installing a new timing drive belt timing marks TM must be aligned as shown the arrow cast into top of pulley points toward crankshaft as shown in Fig M7 20 Install drive belt and flywheel with timing marks aligned as shown at TM To install the distributor to the drive pulley and housing align drive end of dis tributor shaft as shown in Fig M7 22 NOTE The arrow indicates direction of boat travel in forward gear Firing order is 1 4 5 2 3 6 for Merc 800 850 or 1000 or 1 6 4 2 5 3 for other models TIMING Maximum timing advance is 3242 BTDC for Merc 650 Merc 1000 and the 1963 90 cu in Mere 850 Maximum advance for Mark 30H and Mark 55H is 402 BTDC and for all other four and six cylinder models 3442 BTDC The advance t
8. pin 32 Disassemble the propeller shaft by re moving the snap ring and shims early models or the nut 14 Fig M7 33 late models then pressing bearing off geor 7 Check to see if nut 14 is right hand or left hand thread Nut is stamped LH if secured with left hand thread After bearing is removed withdraw the pin 8 and press gear 7 from shaft The pin is normally a loose fit and is retained by the bearing If pin cannot be jarred out remove by inserting a small punch in hole on opposite side of gear and shaft On early models without extra hole the pin must be drilled out if excessively tight To disassemble the drive shaft remove the water pump stud nuts and disassemble the water pump as it is removed Remove nut 6 from lower end of drive shaft secure upper end of shaft in a protected vise then tap gearcase from shaft using a soft mallet Shims 2 control the mesh position of the drive pinion Mesh position can be deter mined by making a trial installation of drive shaft and bearing using the removed shim pack Install drive pinion 5 and in SERVICE MANUAL stall and tighten the retaining nut 6 As semble propeller shaft gear 7 to shaft 9 insert the assembly without bearing into gearcase and check for full engagement of gear teeth Add or remove shims 2 as required Install adaptor ring 11 bearing 12 washer 13 and nut 14 on propeller shaft and tighten and sec
9. plate until 74 inch clearance exists between pickup finger 4 and pickup pin 2 Secure advance plate in this position On older models move the speed control lever slightly toward Slow position and check the adjustment of the latch spring as OLD OUTBOARD MOTOR Fig M7 10 Reverse throttle pickup adjust ment used on older models 1 Reverse lever 2 Reverse pickup finger shown in Fig M7 9 Hold the speed control sector and move the distributor body coun ter clockwise toward the advance stop Note the clearance between latch spring L and sector pin P while torque is applied The spring should latch over the pin with no more than 1 64 inch clearance between pin and latch spring Adjust by loosening the screws retaining latch L to distributor After the adjustment is made move control lever until distributor advance stop contacts the crankcase then adjust the screw A until latch L is unhooked from pin P Synchronize the reverse throttle mecha nism with motor in operation as follows Loosen the screws which retain the reverse throttle lever 1 Fig M7 10 to the sector gear and move the lever as far as possible away from throttle reverse pickup 2 Ad vance the distributor in the Reverse di rection until engine speed is 1000 rpm Move the lever 1 until it just touches re verse pickup 2 and tighten the screws Limit the maximum reverse speed to 4000 rpm or less by moving the lever stop on the lo
10. view of diaphragm type fuel pump Pump body mounts on side of cylinder block and is ported to two crankcases as shown Six cylinder models use fwo pumps 1 Pressure ports D Malin fuel chamber 2 Diaphragm fi Outlet check valve 3 Booster chamber 7 Inlet check valve 4 To carburetor 8 Fuel inlet 108 Fig M7 18 Exploded view of fuel pump and as sociated parts Pump body Valve gasket Outlet check valve Inlet check valve Retainer Gasket Diaphragm Gasket Outlet hose 10 Inlet hose 11 Spring 12 Adapter valve 13 Adapter Seana VtAacis position Adjust the idle stop screw 3 to cbicin an idle speed of 500 rpm in forward gear with motor at operating temperature REED VALVES The inlet reed valves are located on the crankshaft second and fourth main bearing assemblies on four cylinder models and on the second fourth and sixth main bearings on six cylinder models Each reed valve unit supplies fuel mixture from one of the carburetors to the two adjoining cylinders Reed petals RP Fig M7 16 should be perfectly flat and have no more than 0 007 clearance between free end of reed petal and seating surface of center main bearing The reed stop RS must be carefully ad justed to pinch on Merc 650 and 1000 and inch on other models This clear ance is measured between end of stop and seating surface of reed plate as shown at A Seating surface of bear inj must be smooth and flat
11. yee 90 Dwell 90 Dwell 90 Dwell 90 Dwell Carburetor MS Foor ccccacG ic reese yra Tillotson Tillotson Tillotson Tillotson Fuel Oil Ratio 025 05 PEPE ENE TENE 20 1 20 1 20 1 See Text Piston Rings End gap Coe e reer ewenenanees Publication Not Authorized by Manufacturer Side cl aront ssssrssissrserssso Piston Skirt Clearance s ssssssssse Crankshaft Bearing Type Top Main Bearing 0eu8s Ball Bearing Ball Bearing Ball Bearing Ball Bearing Main Bearing 2 4 amp 6 _ Bushing with Reed Valve Main Bearing 3 amp 5 05 Roller Roller Roller Roller No Usad Bath sicisecino iiir 56 56 56 56 Bottom Main Bearing 4 Ball Bearing Ball Bearing Ball Bearing Ball Bearing Crankpin 0ee0esceeeeee Roller Roller Roller Roller No Each Rod ww ccccccceenawees 25 25 30 30 Piston Pin Bearing ses5 Roller Roller Roller Roller No used each sscriiissscreresas 22 22 25 25 TIGHTENING TORQUES All Values In Inch Pounds Unless Noted Connecting Rod cosssssesrrsisssssere 180 Flywheel Nut 70 hp and below 65 Ft Lbs 80 hp and up csuweeuneees 85 Ft Ibs Reed Valves wean ERRE H Li Crankcase Screws sssssseesrrers gt 150 Cylinder Cover socssccresssserssrero 60 Erhgusi Cover ios aleetawesieseaees 60 Intake Manifold sssssssssss gt 45 60 Spark Pig ciicscacescwwes EAEan
12. 2 Impeller 33 Drive pin 44 Insert 35 Cartridge a6 Key a7 Ol seal 41 Shim a8 O ring 42 Inlet tube 39 Retaining ring 43 Gearcase 40 Ball bearing H Water inlet j 11 12 14 f fika OLD OUTBOARD MOTOR models not equipped with propeller hub exhaust the cap screw on trailing edge will be found in exhaust outlet Remove the housing plugs and drain the housing Secure the gearcase in a vise be tween two blocks of soft wood with pro peller up Wedge a piece of wood between propeller blade and anti cavitation plate to hold propeller then remove propeller nut and propeller Overhaul the unit as outlined in the ap propriate following paragraphs Gear Shift Type Measure and record the backlash in forward and reverse gears be fore disassembling the gearcase To dis assemble the gearcase after the propeller is removed clamp the housing in a pro tected vise and remove the gearcase cover 50 Fig M7 29 or 62 Fig M7 30 with a suitable spanner wrench such as 91 22119 for four cylinder models or 91 30291A for six cylinder models Grasp the propeller shaft in the vise and remove shaft and bear ings by tapping housing off with a soft mallet Forward gear 13 Fig M7 29 or 24 Fig M7 30 will remain in housing On four cylinder models remove the adapter ring 25 Fiq M7 29 and save the shims 24 Shims control the backlash of reverse gear 23 Clutch dog can be removed from propeller shaft by r
13. 240 103 Mercury Four amp Six Cylinder 1955 1965 LUBRICATION The power head is lubricated by oil mixed with the fuel For motors with Quick silver lower units one 12 ounce can of Formula 2 Quicksilver 2 cycle engine oil should be mixed with each gallon of gaso line Other oils and fuel oil ratios are not recommended for these motors For motors except those with Quick silver lower unit observe the following If Formula 2 Quicksilver two cycle en gine oil is used one 12 ounch can should be mixed with each 2 gallons of gasoline li Formula 50 Quicksilver oil is used on 1963 and later motors one 12 ounce can should be mixed with each 5 gallons of gasoline If Quicksilver oil is not avail able a good grade non detergent SAE 30 motor oil may be substituted by increas ing oil ratio to pint oil with each gal lone of gasoline 1 16 ratio The lower unit gears and bearings are lubricated by oil contained in the gear case Only EXTRA DUTY Quicksilver Outboard Gear Lubricant should be used Gear case is filled through the filler hole until lubricant reaches the level of the vent hole NOTE On most models the plugs are lo cated on port side of gearcase If both plugs are the same height the forward plug is the filler hole If one plug is above the other the LOWER plug is the filler hole Lubricant should be maintained at level of vent plug FUEL SYSTEM CARBURETOR Tillotson
14. Mercury Four amp Six Cylinder 1955 1965 OLD OUTBOARD MOTOR MERCURY FOUR amp SIX CYLINDER MODELS 1955 1965 FOUR CYLINDER MODELS Year Produced LOD PELIE eo Aas wig TAAIE EA A eeshe Mk S5 ewe MOSS eeressrrinsssssrinrnennnanananana ME 30 30H Me 55 SSH pscersse O o ansaketa ET Cmte e ea Mk 30 30H Mk 55 55H TA HETES ana aa aia ool TSE E ETE S Mk 30 30H Mk 55 55H Mk S38 4 ua TOSO anana aaa ai Mk 35A Mk 55A 58A PAAA AA lIin a an Naa arar Merc 300 Mere400 eeucees esaeran LEO Ra weee SER Ebene Merc 350 Mere 400 500 uausasaaa A E E N E TAEA S o E O vcacatewey acer Merc 450 500 psssses PAE ATS CC pE Aarra ae aoaaa Eaa aea Merce 500 Mere 650 MONS iste pea keke oe ane gx es a SE See A Merc 500 Merce 650 BD 0008 aah 0a eR CR TEE OES aaa aire at Merc 500 Merc 650 CONDENSED SERVICE DATA TUNE UP Rated Horsepower 00 30 35 40 40 50 65 Rated os eh ra nnn 5400 9900 5800 5500 5800 5200 Bore iInches sssesssesrrrrere 2 7 64 27r 2y5 27 Stroke Inches ARETE 21 21 21 2 3 Displacement Cu In 29 78 39 6 44 60 PS OBE occas cake eee sete 1 3 2 4 __ _ Compression a Cranking Speed _ _ Not more than 15 psi variation between cylinders Spark Plug rrna a EEEE 0 E E E S 6 JJ J amp J J4 Fe ET 054 E A EEN M44C M44C M44C Electrode Qap cs eee eaeuceawas 0 025 0 025 0 025 0 025 IGNITION SYSTEM IE ae sieie aris
15. S PINS RINGS AND CYLINDERS Before detaching connecting rods from crankshaft make sure that rod and cap are properly identified for correct assembly to each other and in the correct cylinder Each piston is fitted with three rings which are interchangeable in the ring grooves and are pinned in place in the piston Piston pin is pressed in piston bosses and secured with retaining rings Piston end of connecting rod is fitted with 25 loose needle bearings in Merc 800 850 amp 1000 and 22 loose needle rollers in other models The needle rollers use the connecting rod bore and the piston pin as bearing races When Fig M7 26 Exploded view of crankshaft and associated parts used on four cylinder Mercury Four amp Six Cylinder 1955 1965 Fig M7 27 Exploded view of recoil starter used on models so equipped Retalner Recoll spring Bushing Sheave Wave washer Pawl Spacer Retalner 9 Washer 10 Wave washer 11 Plate 12 Sheave shaft 13 Cable 14 Handle 15 Anchor aA on hk whe assembling install bearing washers and needle bearings in piston end of connecting rod using light non fibrous grease to hold them in place then install and center the piston pin using Mercury tool 91 2426393 Piston must be installed so that sharp verti cal side of deflector will be to starboard intake side of cylinder block Assemble the connecting rod and piston assemblies together with the main b
16. ada aires area WORRIES Kiekhaefer or FM Kiekhaefer Kiekhaefer PAE a1 PAANS 0 008 0 010 0 008 0 010 0 008 0 010 0 008 0 010 Carburetor POEM PATE E A we r A Tillotson Tillotson Tillotson Tillotson or Carter Fuel ON Hal sasesana 20 1 20 1 See Text See Text SIZES CLEARANCES Piston Rings BAG GGG sw iserieoraaek oekawesieeren Side clOGTANCe cencesacees Publication Not Authorized by Manufacturer Piston Skirt Clearance 00 Crankshaft Bearing Type Top main bearing iis Ball Bearing Ball Bearing Ball Bearing Ball Bearing Intermediate main bearings spades ee Bushing Bushing Bushing Bushing Center main bearing 6 Roller Roller Roller Roller N us d oe ope sik ig asian tieeeaseeee 56 56 28 36 Bottom Main peered Ball Bearing Ball Bearing Ball Bearing Ball Bearing Cromkpin 3c sc0 s Roller Roller Roller Roller No each rod 5 ayaSiepesaere wile 25 25 25 32 Piston Pin Bearing sieusecees Roller Roller Roller Roller No used each 22 22 22 29 tSome early models use 56 boleia TIGHTENING TORQUES All Values In Inch Pounds Unless Noted Connecting Rodis ccs iiy iiiasn 180 Flywheel Nut 70 hp and below 65 Ft Lbs 80 hp and up 85 Ft Lbs Reed Valves ccccecrecccees e JOAD Crankcatie SCrOWS 6 cseeeicviavieevc 150 Cylinder Caveats sciissesicisedewaaieace oes 60 Eehoust COY T ciii rosciri akadan es 60 Intake Mom
17. al Block and ground the other test lead Retard the distributor clockwise until lest bulb lights then move in the advance direction until test bulb just goes out Refer to Fig M7 14 With distributor in previously established intermediate advance position loosen the cap screws S securing pickup plate 2 to distributor body and move the plate until the tab 3 just touches the cluster finger 4 Tighten the cap screws Move the control lever to advance timing until the maximum timing advance screw just touches distributor body and bend the nylon covered pickup pin 5 until a clear ance of 0 0000 0 015 exists between pickup pin and cluster finger 6 Move the speed control lever fully to Fast position and adjust the full throttle stop screw 2 Fig M7 15 to allow the throttle shaft 1 64 inch travel to full open 107 Mercury Four amp Six Cylinder 1955 1965 Fig M7 15 View of stop bracket showing location of throttle stop screws l Spark advance atop 2 Throttle stop 4 Idle stop Fig M7 16 Intermediote main bearing showing inlet reed valves Reed petals RP are right and left hand units When install ing reed petals place the reed with the cut out notch N on the left os shown Adjust free height of reed stop RS 2 3 i LIUU Ale ZA ae MM LL g 4 T aS S amp S Nf 7 SEES j Wao ANNAN PINTO IISA 7 Zid SILILI SS Fig M7 17 Schematic
18. carburetors are used on all models except some Mark 55H motors which use Carter Type N carbure tors Two carburetors are used on four cyl inder motors three carburetors on six cyl inder models Refer to the appropriate fol lowing paragraphs for overhaul and adjust ment procedures Carter Model N 2537S Refer to Fig M7 1 Initial setting is 114 turns open for both the idle adjusting needle 6 and high speed adjusting needle 16 Final adjustment must be made under load after operating temperature has been reached Adjust the high speed needle to provide the leanest setting which will permit full power and acceleration Adjust the idle needle after high speed needle has been adjusted to provide smooth operation under load at slow speeds Clockwise rotation of the high speed adjusting needle leans the mixture Clockwise rotation of the idle needle pro vides a richer mixture To disassemble the carburetor scribe a line on the body and bowl to assure proper assembly then remove the bowl nut and fuel bowl To check and adjust the float level invert the carburetor body with bow removed and measure the clearance be tween nearest edge of float ond gasket surface of body flange This clearance should be 11 64 inch with inlet needle seated Adjust by bending lip of float When installing throttle valve 3 make sure the C trademark is toward idle port Center throttle valve by completely closing 104 Fig M7 1 Expl
19. d on and driven by the propeller shaft as shown Gearcase cover cone 27 has a left hand thread Re move cover cone using Mercury tool 91 24117 or equivalent Lift off caver 24 and remove impeller 20 by prying out with screwdrivers Remove water pump cartridge 18 using Mercury puller 91 24120 Secure propeller shaft 14 in a protected vise and tap housing 7 from shaft with a soft mallet Remove nut from lower end of drive shaft 4 then remove the shaft by tapping on housing 7 to free the pinion and bearing Assemble by reversing the disassembly procedure Adjust the backlash to 0 003 0 005 by adding or removing shims 8 then adjust propeller shaft to minimum end 113 Mercury Four amp Six Cylinder 1955 1965 play by adding or removing shims 10 Shims 8 are available in thicknesses of 0 002 0 003 0 005 and 0 010 shims 10 in thicknesses of 0 993 0 005 and 0 010 STANDARD ROTATION UNIT Refer to Fig M7 33 Measure and record the gear backlash before disassembling the gearcase To remove the propeller shaft clamp the housing in a protected vise and remove the gearcase cover 45 using the appropriate Ball bearing Shim Drive shaft Needle bearing 1 2 3 4 Mercury Gearcase Cover Tool or a suitable 5 Drive pinion spanner wrench Gearcase cover is secured F ras waar by a left hand thread Grasp propeller shaft 8 Drive pin in a vise and remove shaft assembly by si EE aap shaft tappin
20. ded view of crankcase and associated parts used on six cylinder models Four cylinder models are similar ASSEMBLY Because of the two cycle de sign crankcase must be completely sealed against both vacuum and pressure Exhaust manifold and water passages must be sealed against water leakage Whenever power head is disassembled it is recom mended that all gasket surfaces be carefully checked for nicks and burrs which might interfere with a tight seal Machined seal ing surfaces without gaskets should he similarly checked Slight damage can some times be remedied by lapping the surfaces on a lapping block using No 00 emery paper Remove only the high spots without lowering the surface If parts are warped sprung or excessively damaged renew the nars All gasket and sealing surfaces should be lightly and carefully coated with an impervious liquid sealer such as Mercury Gasket Sealer Compound 92 28804 Surface must be completely coated using care that excess sealer does not squeeze out into bearings crankcase or other passages Lubricate all bearing and friction surfaces thoroughly with engine oil Loose needle bearings may be held in place during as sembly by using a light non fibrous grease Check the assembly by turning the crankshaft after each step to check for binding or locking which might indicate improper assembly Remove the cause be fore proceeding After piston and crankshatt assembly is installed and secured ro
21. dentical to shims 16 above the bearing which control shaft end play The two shim packs should not be mired The forward gear 24 Fig M7 30 on six cylinder models can be removed after drive shaft and drive pinion have been removed Forward gear 13 Fig M7 29 on four cyl inder models can usually be removed after drive shaft is out by jarring open end of gearcase on a wooden block If any of the major components are re newed or if incorrect before disassembly the backlash must be checked and adjusted On four cylinder models install forward gear 13 Fig M7 29 and bearing 12 using the same thickness shims 11 as were re moved Temporarily install drive shaft 18 and bearing 40 using the removed shim pack 41 Install pinion 20 and retaining screw 21 then tighten screw Backlash should be 0 003 0 005 and ends of teeth on gear 13 and pinion 20 should be even and fully meshed Adjust backlash by dis assembling then adding or removing shims 11 If mesh position was incorrect add or remove shims 41 Shims are available in thicknesses of 0 002 0 003 0 005 and 0 010 On six cylinder models make a trial as sembly by installing bearing cup 13 Fig M7 30 and shims 12 then forward gear 24 and bearing cone 15 Install drive shaft 20 and bearing 18 using the re moved shim pack 19 then install pinion 22 and nut 23 Tighten the driveshaft nut Insert the stripped propeller shaft 28
22. der load at slow speed Turning idle mixture needle clockwise will lean the mixture On carburetors employing the fixed main jet high speed mixture adjustment may be made for special conditions by changing the size of jet 17 The standard jet should normally be used If motor is operated at altitudes above 2500 feet performance can usually be improved by installing a smaller jet Be sure the same size jet is used in all carburetors on the motor On carburetors employing the fixed main jet initia setting for the idle adjustment needle 16 is one tum open from the closed position Idle needle must be adjusted under OLD OUTBOARD MOTOR Fig M7 2 Exploded view of Tillotson car buretor of the general type used on most models 1 Stralner cover 11 Throttle lever 2 Gasket 12 Throttle shaft 3 Strainer 13 Idle tube 4 Gasket 14 Throttle valve 5 Bowl cover 15 Body Inlet needle amp seat 16 Idle needle T Shaft iv High speed jet A Secondary lever I8 Maln nozzle 0 Primary lever 19 Spring 10 Float SERVICE MANUAL a cmH ALT hm ee i OR N Fig M7 3 Schematic view of float mecha nism showing points of adjustment Refer fo tert A Closing adjustment 8 Secondary lever B Open adjustment 0 Primary lever Inlet needle 10 Float load to obtain smooth operation at slow speeds Turning needle clockwise will lean the mixture The recommended fuel leve
23. e stop screw Adjustment clearance Fy eer Fig M7 7 Throttle control mechanism used on early six cylinder models 1 Actuator assembly 2 Pickup pin 3 Cluster lever 4 Pickup finger fi No 1 pickup pin Mark 30 and 55 Serles Make certain that magneto is properly timed and ad justed then adjust carburetor to obtain a smooth idle speed of 600 rpm Loosen the cap screws retaining the actuating bracket 1 Fig M7 5 to magneto frame and slide the follower roller 3 away from throttle pick up 2 With motor at operating tem perature shift to forward gear and move the speed control lever until engine speed increases to 1000 1100 rpm for Mark 30 30E 30H or Mark 55H with Tillotson carburetor 1100 1200 rpm for Mark 55 and 55E or 2000 2400 rpm for Mark 55H with Carter carburetor With engine speeds as indicated move actuating bracket 1 until follower roller 3 just touches throttle pick up arm 2 then tighten the retaining screws Other Four Cylinder Models First make certain that magneto is properly timed and adjusted With the engine not running slowly move the speed control lever toward the Fast position until magneto advance stop just touches the crankcase Refer to Fig M7 6 Loosen the screws 3 securing the throttle actuator assembly to economizer collar then move the actuator plate until 0 015 clearance A exists between follower 2 and throttle cluster lever 1 Tighten the 106 AJ v
24. earing units to the crankshaft then install the complete assembly in cylinder half of block Piston rings Piston Piston pln Retalner Bearing washer Needle roller Connecting rod Needle roller Crankshaft Intermediate main bearing 11 Reed petal 12 Reed stop 13 Main bearing 14 Outer race 15 Needle roller 16 Retalning ring Se enous i ih models Six cylinder models are similar On four cylinder models No 2 and No 3 piston should be started into cylinders first On six cylinder models No 2 and No 4 pistons should be started first Use the Mer cury Ring Compressor Kit C 91 31461A2 if available or carefully compress each ring with the fingers if kit is not available Thoroughly lubricate pistons and rings dur ing assembly Pistons and rings are avail able in 0 015 oversize CONNECTING RODS BEARINGS AND CRANKSHAFT Upper and lower ends of crankshaft are carried by a ball bearing The second and fourth main bearings 10 Fig M7 26 on four cylinder models or the second fourth and sixth main bearings on six cylinder models also contain the inlet reed valves The third main bearing 13 on four cylinder models or the third and fifth main bearings on six cylinder models each contain two rows of 28 loose needle rollers 15 which ride in a split type outer race 14 held together by a retaining ring 16 The connecting rod for Merc 800 850 and 1000 rides in 25 loose ne
25. edle rollers at piston end and 30 loose needle rollers at crankpin end On other models the connecting rod contains 22 loose needle rollers at piston end and 25 loose needle rollers at crankpin end Check rod for alignment using Mercury Align ment Too 91 28441A1 or by placing rod on a surface plate and checking with a light If bearing surface of rod and cap is rough scored worn or shows evidence of overheating renew the connecting rod In spect crankpin and main bearing journals 111 Mercury Four amp Six Cylinder 1955 1965 li scored out of round or wor renew the crankshaft Check the crankshaft for straight ness using a dial indicator and vee blocks Inspect and adjust the reed valves as outlined in REED VALVE paragraph and reassemble as outlined in ASSEMBLY para graph MANUAL STARTER Refer to Fig M7 27 for a starter of the general type used on models so equipped To disassemble the starter remove the top cowl then remove the screw and trim cap from top to cowl Insert a screwdriver in slot in top of sheave shaft 12 and loosen the shaft nut left hand thread Allow the shaft and screwdriver to tum clockwise until recoil spring 2 is completely unwound Pry the anchor 15 out of starter handle 14 and remove the anchor and handle Remove the nut from upper end of sheave shaft 12 invert the assembly and remove the parts making sure that recoil spring 2 remains in housing recess as sheave 4
26. emoving the retaining ring then 20 37 39 a p 45 Bearing carrier 40 Washer 46 Needle bearing 50 Gearcase cover 47 Oil seal fl Tab washer 48 O ring 52 Propeller nut Fig M7 29 Exploded view of gearcase assembly used on Four Cylinder models SERVICE MANUAL Spacer Reverse lock cam Reverse lock cam Oll asal Bushing Or ring Shift shaft Shift cam Plunger Silde Spring Shim Bearing cup Needle bearing Bearing cone Shim Retaining ring Ball bearing Shim Drive shaft i 1 Needlo bearing 4 Drive pinion Shaft nut Forward gear Retaining ring Clutch dog Cross pin aes Propeller shaft Reverse gear Ball bearing Shim Thrust washer OO rin Guide sleeve Slinger 36 Ol seal Hubber seal Fitting Clamp Inlet line Pump body Insert Impeller Drive pin Gasket Face plate ne Gasket 53 Water pickup amp Pump base trim tab O11 seal H OO ring O ring 55 Needle bearing 5l Gearcase 56 Needle bearing Fig M7 30 Exploded Gasket ee ee ee ee i to 635 Ga Da Go Go a ho to 3 BS fa tI FS m es il m as SHASak OBE OS BOSAe Ooo See ORN N binnnr eho S opanke 8 Tas 1 1 5 19 910 1 j j N DIA i 1415 ae 1455 5 las Mercury Four amp Six Cylinder 1955 1965 25 26 30 3 Ahhh anges 52 We Key dol 63 64 ee 67
27. g housing 38 from shaft with a soft 11 Adaptor ring mallet NOTE On Mere 800 models the 4 ig acre bearing carrier is similar to that shown at 14 Bearing nut 15 Washer 16 Splined washer 17 Tab washer 18 Propeller nut 19 Water tube 20 Pump cover 21 Gaaket 22 Face plate 23 Gasket 24 Impeller 2r Drive pin 20 Insert 27 Cartridge 28 Key 2 Wave washer 30 Cover 31 Carrier 32 Ol seal a3 O ring dd Valve adaptor 25 Shim 36 Water valve 37 Rubber seal 38 Gearcase 20 Water Inlet 40 Needle bearing 41 O ring 42 Bearing carrier 43 Ol seal 44 Washer 45 Housing cover 10 11 12 13 JEN Fig M7 32 Exploded view of Quicksilver gearcase and associated parts used on older models 1 Ol seal B Shim 15 Propeller nut 22 Ol seal 2 Oll sea 9 Driven gear i Sea ing washer 23 Needle bearing 3 Ball bearing 10 Shim 7 Rubber seal 2i Pump cover 4 Drive shaft 11 Ball bearing 18 Cartridge 25 Needle bearing 5 Shim 12 Snap ring 19 Drive pin 26 Oll seal 6 Drive pinion 13 Drive pin 20 Impeller 27 Housing cover 7 Gearcase ld Propeller shaft 21 Cover plate 114 OLD OUTBOARD MOTOR pe LATA ya ah ABMS Fig M7 33 Exploded view of Standard Rotation gearcase and associated parts used on direct reversing models Illustrated is Merc 600 unit 31 Fig M7 34 Carrier can only be par tially removed without first removing dowel locating
28. ide to loosen gasket Lift power head from lower unit and install on a suitable stand Re move the flywheel magneto or distributor alternator generator and the carburetors Ex haust manifold cover cylinder block cover and transfer port covers should be removed for cleaning and inspection Remove the upper and lower crankcase end caps by using a suitable puller at tached to threaded holes in caps Remove the main bearing locking bolts from front crankcase half remove the flange bolts then remove crankcase front half by insert ing screwdriver in the recesses provided on side flanges Use extra care not to spring the parts or to mar the machined mating surfaces The crankcase half 6 Fig M7 25 and cylinder assembly 15 are matched and align bored and are available only as an assembly Crankshaft pistons bearings and con necting rods may now be removed for serv ice as outlined in the appropriate following paragraphs When assembling follow the procedures outlined in the ASSEMBLY para graph 110 Ol seal End cap Shim O ring Ball bearing Crankcase half Dowel pin 8 Ball bearing 9 O ring 10 Shim 11 Oll seal 12 Ol seal 13 End cap 14 Transfer port cover 15 Cylinder half 16 Cylinder cover 17 Check valve 18 Exhaust plate it Exhawst cover S Oo b OH lm F k zm o Bu eo SE Uo OLD OUTBOARD MOTOR n m a Fig M7 25 Explo
29. ifold 600065 45 60 spark Plug Se A i 102 SERVICE MANUAL Mercury Four amp Six Cylinder 1955 1965 MERCURY FOUR amp SIX CYLINDER MODELS 1955 1965 SIX CYLINDER MODELS Year Produced eee BO a R E E mele Ra EO sats MibJSE samaa go s6e 0 gt s 0O wwajec ene CL ee ee Mk75E Mk78E ne A TOE nkri VENE OANE RE Mk75A 78A Senan EEROR Eaa ANE TTN Merc 600 700 Merc 800 ee Wel ee a err Merc 600 700 Merc 800 caaveeue OBS yc ce tarot iGreen caste a naa wees Na Merc 850 Mere 1000 TPES eccraccacwes xanwaseeaeiwane S e O hitneee ces Mere 850 1000 PIGS cineca Ue wm aa aa a iacsettien Merc 850 1000 Ds racine cistice SEER DWE SANG aA qc kie keene Merc 900 1000 CONDENSED SERVICE DATA TUNE UP Rated Horsepower 00e0eeeeeees 60 60 70 80 85 85 100 Rated ii aaa a 5500 5500 5200 5200 Poro fichet inari a 20r 21 2 2 Stroke Inches Sate avaie rw ala 216 216 2 Ve 2 3 Displacement Cu In srsssssss 59 4 66 76 30 Fiing GIGGLE eces pea neenesetse ete 1 6 4 2 5 3 1 4 5 2 3 Compression a Cranking Speed Not more than 15 psi variation _ __ between cylinders Spark Plug Champion pern ighin iaa J6 J amp J J4 J4 f a ae a ETAST Electrode Gap ccncceesereneens 0 025 0 025 0 025 0 025 Distributor WA sca koe Fee sete ste SSAA Own Own Own Own Point GOP sssssssrrresess
30. iming mark is not indicated on flywheel on most models The manu tacturer recommends that the special tim ing gage Fig M7 19 designed for the motor be used This gage is threaded into No 1 top spark plug hole on four cylin der models No 3 spark plug hole on Merc 800 850 and 1000 or No 4 spark plug hole on other models Make sure that center Mercury Four amp Six Cylinder 1955 1965 Fig M7 21 Exploded view of distributor mounting bracket and drive mechanism used on some models Others including mag netos are similar 1 Cap 12 Ball bearing 2 Wave washer 13 Pilot assembly 3 Tab washer id Key 4 Thrust washer 15 Flange plate uo Adaptor 16 Key i Nylon pin 17 Drive pulley T Actuator assembly 18 Thrust washer 5 Advance collar 19 Drive shaft 9 Retalner pin 20 Ball bearing 0 Terminal pin 21 Snap ring 1 F _ Retard spring plunger of gage fils into notches of threaded outer body as shown in left hand view Turn flywheel until piston is at top dead center then thread the gage in or out until crankpin will pass over center while piston is in contact with gage plunger Rotate fly wheel counter clockwise then without mov ing threaded outer gage body depress center plunger and tum 4 turn Rotate fly wheel until piston strikes the plunger to establish crankshaft position for maximum advance timing NOTE If a protractor is used to scribe a degree mark on flywheel for timing p
31. ionable parts should be renewed IGNITION Four cylinder models use a belt driven magneto Six cylinder models use a belt driven distributor Refer to the appropriate sllowing paragraphs MAGNETO Breaker point gap should be set to provide 48 degrees dwell for all models except MK30 and 55 Dwell for Mark 30 and 55 should be 54 degrees Breaker point gap will normally be 0 008 0 010 Dwell plate part number C 91 3184A2 is available for setting angle that brecker points are closed Breaker point spring ten sion should be 33 37 ounces measured from curve of breaker arm next to rubbing block A quick test of magneto condition can be made by removing high tension wire from one spark plug with engine running Spark should jump a pinch gap at idle speed To install the magneto drive belt remove the flange plate on top of magneto pulley then remove the flywheel using a puller Turn the magneto pulley until the arrow cast into top of pulley points toward crank shaft as shown in Fig M7 20 When installa tion is complete flywheel and magneto tim ing marks must be toward each other and on the axis of a line connecting the crank shaft and magneto shaft as shown at TM The magneto shaft has a blind spline which aligns with a similar spline in magneto pulley shaft DISTRIBUTOR Distributors are equipped with two sets of alternate firing breaker points Motor is equipped with two coils each of which is connected to its own set
32. is removed Protect hands with cotton gloves or a cloth grasp recoil spring 2 remove spring and allow it to unwind slowly to prevent per sonal injury Lubricate the parts with Multipurpose Lubricant and assemble by reversing the disassembly procedure Make sure that pawls 6 are all installed the same way with flat radius to outside Install wave washer retainer 9 with cup end up and make sure the tab in spring retainer 1 engages slot in sheave shaft 12 Loosely install the shaft nut pull free end of cable through cowl and install handle 14 and anchor 15 After handle is installed turn sheave shaft 12 counterclockwise with a screwdriver until cable handle is pulled against top cowl then tum shaft an addi tional 114 tums and tighten the shaft nut LOWER UNIT PROPELLER AND DRIVE CLUTCH Pro tection for the motor is provided by a special cushioning clutch built into the propeller hub Propeller is splined to the shaft No adjustment is possible on the propeller or cushioning clutch Various pitch propellers are provided and propeller should be se lected for best performance under appli cable conditions Propellers other than those designed for the motor must not be installed R amp R AND OVERHAUL Lower units are divided into two main types the gear shift type used on early models late four cylin der motors and late six cylinder Full Gear Shift motors and the straight drive type used on direct reversing m
33. ket Oo 2 o5 ca de od to Model KA 13A Main jet res th ht oe ee Model KA 14A Main jet Mods KA I6A Main jet Mode KA 17A Main jet eo Model KA I8A Main jet Model KA 19A Main jet Penne mate laaieatvcahs Model KB 2A Main jet Model KB 3A Main jet rrr 3s oh Pe ee EREHE Model KC 1A Main jet EEEE A TNE i Model KC 2A Main jet 2 Model KC 3A Main jet Model KC 5A Main jet Model KC 6A Main jet iconas Model KC 7A Main jet o oonn p onnnn naaar nn a 0 065 SPEED CONTROL LINKAGE The speed control lever is directly attached to the magneto or distributor to advance or retard the ignition timing The throttle valve is synchronized to open as the timing is ad vanced It is extremely important that ig nition timing and throttle valve opening be correctly synchronized to obtain satisfactory operation When synchronizing the speed control linkage first adjust the timing as outlined in the IGNITION section then pro ceed as outlined in the appropriate follow ing paragraphs Fig M7 5 Speed control mechanism used on Mark 30 amp 55 series Refer to text for details 1 Actuating bracket 2 Throttle pickup 3 Follower roller 105 Mercury Four amp Six Cylinder 1955 1965 AA A 3 Wo ES ore So SP a id yf on Fig M7 4 Throttle control mechanism used on late four cylinder models Cluster finger Pickup pin Adjusting cap screw Full throttl
34. l is approxi mately HH inch below gasket surface of float bowl To adjust the float remove bowl cover 5 and refer to Fig M7 3 Invert the cover and with inlet needle 6 closed measure the distance between primary lever 9 and gasket surface of bowl cover as shown at A This distance should be j inch if it is not bend the curved tang on secondary lever 8 until correct measure ment is obtained After adjustment is made bend the vertical tang on primary lever 9 to allow a maximum clearance B of 0 040 between the secondary lever 8 and inlet needle 6 The contact spring located in float should extend 5 64 inch above top of float 10 Check to see that spring has not been stretched or damaged center of Stendard main jet size diameter for car buretors with fixed type main jet 17 Fiq M7 2 are as follows Model AJ 54A Main jet 0 055 Model AJ 55A Main jet SEFE 0 055 Model KA 2A Main jet 0 063 Model KA 7A Main jet 0 081 Model KA 8A Main jet 0 061 Model KA 3A Main jet 0 061 Model KA 10A Main jet 0 065 Model KA 11A Main jet 0 065 Mode KA 12A Moin j t vn we we mequnceneeeeecenyes 0 061 Mercury Four amp Six Cylinder 1955 1965 Fig M7 4 Carburetor connecting linkage used on six cylinder models Four cylinder models are similar Choke solenoid Plunger Choke button Link Choke rod Choke valve Carburetor Cluster lever Clamp Pickup brac
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36. nits then withdraw the propeller shaft Adjust the gear backlash by adding or removing shims 8 NOTE Adding shims will DECREASE the backlash on Counter Rotation units Mercury Four amp Six Cylinder 1955 1965 TY SNNN Fig M7 34 Exploded view of Counter Rotation gearcase and associated parts used on direct reversing models Illustrated is Merc 800 unit AGAR HH OD T OS Om Con Snap ring Ball bearing Shim Drive shaft Needle bearing Drive pinion Shaft nut Shim Driven gear Drive pin Propeller shaft Washer Ball bearing Tab washer Bearing nut Thrust hub Cupped washer 18 19 21 Ci aed i J 29 30 a1 da dd H Cupped washer Propeller nut Cap Gasket 22 23 24 25 26 Pump cover Ol seal p ring Shim Gearcase Needle bearing rage ring Spacer Needle bearing Bearing carrier Locating pin Needle bearing Ol sen ca 36 3T 38 39 40 41 42 43 44 45 46 dT 48 40 50 Sealing sleeve D ring D ring Washer Housing cover Facing plate Gasket Impeller Drive pin Insert Pump body Inlet line Water valve Valve adaptor Shim Water Inlet 115 Copyright of Old Outboard Motor Service Manual 1st Editon Volume 2 is the property of Penton Media Inc Clymer and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder s express writte
37. oded view of Carter carburetor used on some Mark 55H mod els l Throttle shaft 2 Spring 3 Throttle valve 4 Body 5 Spring Idle needle 1 Choke detent 8 Choke valve o Choke shaft 10 Inlet needle amp sent 11 Main nozzle 12 Float shaft 13 Spring 14 Float 15 Gasket 16 High speed needle Cap screw throttle while tightening screws Always use new screws to secure the valve Tillotson Carburetors Fig M7 2 shows an exploded view of carburetor typical of that used on all models Minor difference will be apparent upon examination AJ 4A9A car buretors used on some early models do not use the fuel filter 1 through 4 Some early carburetors employ an adjustable high speed needle instead of the fixed jet 17 Initial setting for carburetors equipped with the high speed adjustment needle is one tum open from closed position for the idle needle 16 and 12 tums open for the high speed adjustment needle which re places the high speed jet 17 Run motor until operating temperature is reached then shift to forward gear and open the throttle Slowly turn the high speed adjustment needle clockwise until engine misses then back needle out approximately 1 turn Ad just the high speed needle for all carbure tors in the same manner for equal per formance After high speed needles have been properly adjusted regulate the idle adjustment needles 16 for all carburetors until engine runs smoothly un
38. otors Direct drive models are further subdivided into standard rotation and counter rotation types which are desiqned to be paired for twin motor installation Most service on the lower unit can be performed by detaching the gearcase hous ing from the driveshaft housing When re moving the housing check carefully at the locations shown in Fig M7 28 to make sure that all securing cap screws or stud nuts are removed On some early motors the gearcase housing was secured by two 112 Fig M7 28 View of typical lower unit showing location of attaching screws secur ing gearcase housing Refer to text for details studs On some later units securing studs will be found at all of the indicated loca tions NOTE On motors equipped with trim tab on water intake as shown at 4 remove the intake by removing plug and screw on top side of anti cavitation plate then check for cap screw under water intake On Reverse lock cam 2 Reverse lock cam 3 Ol seal 4 Bushing i O ring G Shift shaft 1 7 Shift cam o 8 Shift plunger 2 9 Slide os 3 10 Spring o j 11 Shim On 12 Ball bearing 13 Forward gear 6 14 Needle bearing 15 Retalning ring 16 Clutch dog 17 Cross pin 18 Drive shaft 19 Needle bearing 20 Drive pinion 21 Cap acrew 22 Propeller shaft 23 Reverse gear 24 Bhim 25 Adaptor ring 26 Ball bearing 27 O ring 28 Slinger 29 Ol seal a0 Cover 31 Outlet plate
39. p finger 2 on throttle shaft until it contacts pickup stop 1 and tighten the clamping screw Remove the drill Fig M7 14 With distributor in interme diate advance position loosen screws 5 and reposition pickup plate 2 until tab 3 just touches cluster finger 4 Carburetor cluster Pickup plate Pickup tab Cluster finger Pickup pin Cluster finger Cap screws O TA d bja el Merc 700 800 850 1000 Full Gear Shift rizs make sure that distributor is properly limed and adjusted Correct synchroniza ton requires that an intermediate timing cdvance position of 0 015 inches for piston crown before TDC be determined This is most conveniently done by using the spe cial Mercury Timing Gage Part No 91 3116141 and a continuity timing light Make sure center plunger of gage is seated in notches of threaded outer case and thread the gage into No 4 spark plug hole for Merc 700 or No 3 spark plug hole for other models Turn flywheel until the respective piston is in approximately Top Dead Center position then thread the gage in or out until crankshaft will rock over TDC while piston crown is in contact with gage plunger Rotate crankshaft counter clockwise then without moving threaded portion of gage depress center plunger and turn plunger 4 tum Rotate flywheel clockwise until piston crown strikes the plunger Attach one lead of timing test light to the No 1 Coil Primary White lead of Termin
40. tate the shaft until each piston ring in tum appears in one of the exhaust ports then check by pressing on ring with a blunt tool Ring should spring back when re leased if it does not a broken or binding ring is indicated and the trouble should be corrected The recommended crankshalt end play of 0 008 0 012 is controlled by means of shims 3 amp 10 Fig M7 25 placed under each crankcase end cap Shims are available in thicknesses of 0 002 0 003 0 005 and 0 910 and a shim pack of approximately equal thickness should be used under each end cap To check the end play temporarily install the crankshaft and end caps on the cylinder block omitting the sealing rings 4 amp 9 Use the removed shims in the trial installation Install and tighten the end cap retaining screws Tap the crankshaft each way with a plastic hammer then measure the clearance between ball bearing inner race and thrust face of crankshaft using a SERVICE MANUAL feeler gage Determine the shims to be added or removed then equalize the shim pack thickness on final assembly Tighten the crankcase exhaust cover and cylinder cover cap screws by first tighten ing the center screws then tightening screws evenly working toward top of power head When upper half is tightened again start at the center and tighten screws alter nately toward bottom of power head Tight ening torques are given in the CONDENSED SERVICE DATA table PISTON
41. top bracket against crankcase COOLING SYSTEM WATER PUMP The rubber impeller type water pump is contained in the lower unit gearcase housing and can be removed after removing the gearcase The pump housing is offset in relation to the driveshaft of pro peller shaft as shown in Fig M7 24 The water pump on direct reversing models con tains a valve which permits reversal of water pump rotation without affecting water flow 109 Mercury Four amp Six Cylinder 1955 1965 Fig M7 24 Schematic view of rubber im peller type water pump Flexing of impeller blades in offset housing causes water to be drawn through inlet ports IN and forced into power head through outlet ports OUT At high speeds blades remain curved as shown by broken lines HS and pump becomes a centrifugal pump When cooling system problems are en countered first check the water inlet for plugging or partial stoppage then if not corrected remove the gearcase housing as outlined in LOWER UNIT section and ex amine the water pump water tubes and seals The water inlet is located on the anti cavitation plate immediately above the propeller POWER HEAD R amp R AND DISASSEMBLE To remove the power head assembly first remove the top and side cowling remove the electric starter assembly then disconnect all interfering wiring and linkage Remove the stud nuts which secure the power head to lower unit then jar power head on exhaust s
42. ure the nut Install the assembly in gearcase using the shims 10 which were removed Tap the shaft securely into place and check the backlash which should be 0 003 0 005 If backlash is not correct add or remove shims 10 as re quired Shims are available in thicknesses of 0 002 0 003 0 005 and 0 010 on Merc 800 models and 0 002 0 003 and 0 005 on other models When assembling the water pump check the neoprene water valves 36 to be sure they are in good condition Install the adaptors 34 so that flat sides are together using a sufficient quantity of shims 35 to bring top surface of adaptors even and flush with top of housing Shims are avail able in thicknesses of 0 003 0 005 and 0 010 COUNTER ROTATION UNIT Refer to Fig M7 34 Service and adjustment procedures are similar to that of Standard Rotation Units covered in the preceding paragraph Follow the procedures outlined in the pre ceding paragraph except for the following differences Propeller shaft cannot be withdrawn until after driveshaft is removed After re moving the housing cap 39 withdraw bearing carrier 31 Bend down the lock ing tabs on washer 14 then remove nut 15 Remove ball bearing 13 and adaptor 12 using Mercury puller 91 29456A3 If puller is not available jar the end of pro peller shaft sharply on a block of wood to dislodge the bearing After bearing has been removed remove the drive shaft as outlined for Standard Rotation U
43. urposes be sure to check for proper TDC position The timing mark in scribed in the flywheel is for magneto or distributor INSTALLATION purposes only The No 1 piston is 20 ATDC on most models when magneto or distributor timing marks are aligned Fig M7 22 To install and time the distrib utor on direct reversing models turn the drive tang until the offset end of tang faces forword as shown at A On gearshift models cut out notch should be facing for ward as shown in view B Align pulley timing marks as shown in Fig M7 20 Fig M7 23 Distributor cap is marked as shown for installing spark plug wires The inside numbers A are for early 60 and 66 cubic inch motors The outside numbers B are for 76 cubic inch and larger motors except those with Thunderbolt ignition Numbers c inside the squares are for Mere 95055 and 110055 models with Thunderbolt ignition With the advance timing position estab lished connec a continuity test light to the No 1 Coil Primary White Lead on distributor models or to primary ground terminal on magneto models Attach the other test lead to a suitable ground Rotate the magneto or distributor body clockwise until points are closed as indicated by com tinuity light then counter clockwise until points just open Limit magneto or distrib utor advance at this point by means of the spark advance stop screw 1 Fig M7 15 on models so equipped or by sliding mag neto s
44. wer cowl Merc 600 700 and 800 Direct Reversing First make certain that distributor is prop erly timed and adjusted To synchronize the forward throttle refer to Fig M7 11 With the engine not running move the speed control lever until distributor pilot just touches the maximum advance stop screw Loosen the screws S attaching pickup plate 2 to the sector gear and move the plate until the nylon covered pickup pin 5 is not touching the cluster finger 6 then bend pickup tab 3 in or out until a No 48 twist drill 0 076 gage can just be inserted between port side of throttle valve and car buretor barrel as shown at D Remove the drill or gage Move the speed control lever to retard the ignition until spark occurs at 0 030 inches before TDC of piston NOTE This intermediate timing advance position can be determined using Mercury Timing Gage 91 31161Al for gear shift SERVICE MANUAL Fig M7 11 Forward throttle control mech anism used on late models Refer to text for method of adjustment 1 Cluster lever w Pi kup pin a Pickup plate Pickup finger 3 Pickup tab D Drill gage 4 Pickup finger 5S Attaching acrew models or 91 30290Al for direct reversing models Thread timing gage into No 4 from top spark plug hole on Merc 600 or 700 models or No 3 spark plug hole for Merc 800 models Make sure that center plunger of gage fits into notches of threaded outer body Turn flywheel
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