Riley 2.5_A

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    ASECTION   A

    TIlE   ENGINE(2~   LITRE)

    General   Description.

    The   Lubrication  System.

    Section   No.  A.  I

    Section   No.   A.2

    Section   No.   A.3

    Section   No. A.4Section   No.   A~5

    Section   No. A.6

    Section   No. A.7

    Section   No.  A.8

    Section   No.  A.9

    Section  No.  A.IO

    Section   No.  A.l   I

    Section   No.  A.12

    Section   No.  A.13

    Section  No.  A.14Section   No.  A.15

    Section   No.  A.16

    Section   No.  A.17

    Section   No.  A.l8

    Section   No.  A.19

    Section   No.   A.20

    Section   No.  A.21

    Section   No.  A.22

    Section   No.  A.23

    Section   No.  A.24Section   No.  A.25

    Section   No.  A.26

    Section   No.  A.27

    Section   No.  A.28

    Section   No.   A.29

    Section   No.   A.30

    Section   No.  A.3 I

    Section   No.  A.32

    Section   No.  A.33

    Section  No.  A.34Section   No.  A.35

    Section   No.   A.36

    Section   No.  A.37

    Draining the  engine   sump.

    Removal and   replacement  of the  sump.

    Removal and   replacement  of the  oil   pump.

    Dismantling   and   reassembling   the oil   pump.

    The  oil   pressure  release  valve.

    Removal and   replacement  of the  main bearings.

    Removal and   replacement  of the   cylinder  head.

    Removal of  piston  and  connecting rod.

    Removal   a!ld   replacement   ofthe   piston   rings.

    Fitting   the gudgeon  pins and   reassembling   piston  and   connecting   rod.

    Removal   and   replacement   ofthe carburetters.

    Removal  of the inlet  manifold.

    Removal  of the  exhaust   manifold.

    Removal   and  dismantling  of the water pump.Setting  the  tappets.

    Removing the  dynamo  belt.

    Removal of the  crankshaft   pulley.

    Removal of the timing  chain  cover.

    Removal of the  crankshaft   chain wheel.

    Removal and   replacement of the timing  chain.

    Removal of the  chain tensioner.

    Removal  of a   camshaft.

    Removal  of the rocker gear.

    Removal   of the   valves.Removal   and  refitting of   the   valve guides.

    Decarbonising.

    Grinding   and   testing the   valves   and   their  seatings.

    Adjusting   the fan   belt.

    To   dismantle  the   fan assembly.

    Removal   and   replacement of the  engine   and gearbox.

    Removal of the clutch.

    Removal  of the  flywheel.

    Removal  of the crankshaft.

    Oil   pressure.

    Regrinding   the  crankshaft.

    Locating  troubles.

    Piston  sizes and   cylinder  bores.

    A.   I

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    A   TIlE  ENGINF~GENERAL DESCRIPTION

    The   four-cylinder,  overhead  valve   engine   is   built   inunit  construction  with   a four-speed gearbox.

    It   has   a   robust   four-throw   crankshaft   carried   inthree   main bearings   which   are   thick   white-metal-lined   bronze   shells   dowelled   in the   crankcase. Therear   bearing takes   the   end   thrust, the   bearing beingflanged at   both   ends.

    The   connecting rod   big-ends are   white-metalleddirect  and the  gudgeon  pin   is   a  floating fit   in the   littleend,   being   retained   by  circlips.

    The   pistons   are   of  aluminium   alloy   and are   fitted

    with two   compression  and   two oil  control   rings.Each   camshaft  is  supported   in   three   bronze   bushedbearings   and   is   driven from   the   crankshaft by   means

    of   an   endless   duplex   roller   chain.The   valves are   operated   from   the   camshafts   via

    hollow   cylindrical   tappets,   short,   light  push-rods   and

    rockers.   Tappet   adjustment takes  place at   the rocker.Cooling   is   by  pump   and   fan-assisted thermo-syphon

    action.

    THE   LUBRICATION   SYSTEMAn   illustration   of the   lubricating   system   appears

    on page   A.26.The engine   oil   is   carried   in   the   ribbed aluminium

    sump   below   the   crankcase and   an   oil level   dipstickis   fitted to the   left-hand   side   of the block.   The   com-bined   oil   filler   and crankcase   breather   is   also on   theleft-hand   side  at   the  front  of the  engine.

    The   submerged,  self-priming,   gear-type   oil   pump   isbolted   to the  under   face  of the   cylinder block   and   Isdriven   by   a   skew gear   on   the inlet   valve camshaft.

    From   the  pump,  oil   is  delivered   by   an  external  pipeto   a full-flow filter.   From   the   filter another  externalpipe  leads to the crankcase side and   thence via   internal

    oilways to the   main   bearings.

    The big-end bearings  receive oil by  means of  oliwaysdrilled   in  the  crankshaft.   Camshafts,   timing  chain   androcker-shafts  are  supplied   by  means of   internal oilwaysdrilled  in   the  crankcase.

    The  oil   pressure  release   valve   is   located   just  behind

    the  exhaust  pipe.

    Section   A.l

    DRAINING   THE   ENGINE   SUMPThe  sump  on   new   and   reconditioned   engines   must

    be   drained   and   refilled   with   new   oil   after   the first

    500   miles   (800   km.)   and   then   at   intervals   of   every~,000 miles   (5000   km.).   The hexagon-headed   drainplug   is   situated   on   the   right-hand   side   of   the   sump.

    The  oil should   preferably   be  drained when   the  engineis   hot,   in   which  condition   the  oil   flows more   readily.

    Unless   the   sump   is   to   be   removed   and  cleaned,   itshould   be   allowed   to   drain   for   at   least   ten   minutesbefore   the   drain   plug   is   replaced.   When   the   sumphas   been   drained,  approximately   14  pints   (8   litres) ofoil   are   required   to refill   it.

    REMOVAL   AND   REPLACEMENT OF THESUMPTo clean the  sump, take  out the  drain plug   and allow

    the oil to   drain  away.   The  sump   is   located   by  sixteenhexagon-headed   bolts   and   spring   washers   insertedfrom   the   underside   of the   flange. Removal   of   theseallows the   sump   to   be   withdrawn.   Remove   the trayand   thoroughly   clean   the   sump   with   paraffin   and   a

    clean brush.When   the sump   has  been   dried,   refit the   tray  and

    drain   plug.No   gasket   is   fitted   on   early   models,   but   jointing

    compound   is   used   to   make   the   joint.   Make   sure   alltraces   of the   old   compound   are   removed   beforerefitting   the   sump.

    Later   models make   use   of   a  gasket   and   a   new   oneshould  be used  when   replacing the sump on   all   models.

    Section   A.3

    REMOVAL   AND   REPLACEMENT   OF   THEOIL   PUMP

    Remove   the   sump   as   detailed   in   A.2   and  then   takeoff the drive   shaft   top   cap   located   near   the  top   and

     just  behind   the  oil   filter.Take  off the  pump   flange   nuts   and  washers   and  thentap   the   drive   shaft   down,   when   the   whole   pumpassembly,,  complete   with   shaft   and   gear,   will   comeaway   from   its   spigot   on   the   crankcase.

    (2+   LITRE)

    Fig.   Al.

    The  engine   drain   plug.

    SectiolR   A.2

    A.2

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    (2~  LITRE)   TIlE   ENGINE  A

    Section   A.4

    DISMANTLING   AND   REASSEMBLING

    THE   OIL   PUMPRemove   the oil   pump   as  detailed   in A.3   and  take off

    the   coarse mesh screen   surrounding   the   pump   body.Next,   take   off   the   bottom   cover   and   tap   the  shaft

    downwards   so   that the   gear   is   exposed.   Tap   thedriving  gear   down  the  shaft   to   a   collar  to   give   accessto the  retaining   split   ring   and   extract   the split   ringholding  the driving  gear   in   position.   Pull  off   the  gearwheel   and   remove   the   Woodruff  key,   then   pull   out

    the   shaft.

    Fig.   A.3.Checking   the   end   float on the oil   pump   gears.

    Ensure   that   the   cover-plate   and   pump body   faces

    are  perfectly   clean   before reassembling.   They   form   ametal-to-metal  joint  and   no  gasket or sealing com  pound

    must   be   used.When   refitting   the cover-plate take   special   note  of

    the  two  dowel  pins.

    Fig.   A.4.

    Checking   the diametrical   clearance   between   the oil

    pump   gears  and   the oil   pump body.

    The skew  gear  at  the top of  the  driving shaft   is  keyed

    and pinned in   position.   The   bush  is  pinned   in  position.The   driven   gear   is   bushed   and   runs   on   a   spindle

    which   is   pressed   into the   pump body.To  check  the   gear clearances,   the   pump  body,   gears

    and shaft should   be   cleaned   carefully   and   reassembledbefore   carrying   out the   following   procedure

    I.   Measure the  diametrical  clearance   between theteeth  of the   gears  and   the   pump   body   (see   Fig.A.4).   This   should   not   be   more   than   006   in.(.15  mm.).

    2.   Check   the   end   float  on   the   gears   by   placing   astraight-edge across   the face   of  the   pump   body,

    and   measuring   the   clearances   with   feelers,   asshown   in  the  illustration   (Fig.   A.3).   This shouldnot   be   more   than   .003   irr. (.08   mm.).

    Fig.   A.2.The   cap   on   the   oil   pump   shaft.

    Fig.   A.5.Exploded   view of the oil   pump.

    A.3

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    (2{   LITRE)A   THE   ENGINE.Section   A.5

    THE   OIL   PRESSURE   RELEASE   VALVE

    This   is   provided   to   prevent   the   building   up   ofexcessive oil   pressure  when  the oil   is cold.   It is   locatedon   the   left-hand  side   of the   engine behind   the   exhaust

    pipe.To adjust the  release  pressure the  locknut  should  be

    slackened   off and  the  grub   screw turned   in the  appro-priate   direction.   Screwing   the   grub   screw   inwardsincreases  the   release   pressure.

    To   dismantle   the   assembly   the   large   nut   must   be

    unscrewed   and   the   grub   screw   removed.   After thattake  out the  spring collar, spring  and square   plunger.The actual valve seating   is   pressed   into   the  crankcase,but is renewable.   The normal oil  pressure  is  30  lb./sq.in.

    at   40   m.p.h.   (2.11   kg./cm.5   at   64   k.p.h.).

    The   release  valve seating   is  removable by tapping thehole   in   the   seating   ~  in.   B.S.F. and  then   using   a   boltand   nut  for withdrawal   purposes.

    Adjustingscrew

    Fig.   A.6.

    The   release  valve   assembly.

    Section   A.6

    REMOVAL   AND   REPLACEMENT   OFTHE   MAIN   BEARINGS

    The crankshaft   has   three  main bearings   consisting  ofthick  bronze  shells, white-metal   lined.   They cannot  be

    changed   whilst   the crankshaft   is   in  position.The top   halves  of  all   bearings are   dowelled   in   posi-

    tion,   as   are   the   two   lower   halves   of the front   andcentre   bearings.

    To remove   the   bearings,   take  out   the split pins   andremove   the   castellated   nuts.   Take   off   the   bearingcaps   and   lift   out   the   crankshaft,   having   previously

    removed  the timing  chain   as   detailed   in   Section   A.20,

    the   clutch   and   flywheel   as   detailed   in   Sections   A.31and   A.32,   and   the   pistons   and   connecting   rods   as   inSection   A.8.

    New   bearings   are   supplied   with   a  fitting   allowancefor line-boring  or  hand-scraping.

    Section   A.7

    REMOVAL   AND   REPLACEMENT OF THECYLINDER   HEAD

    Drain   the water from   the  cooling   system   by   meansof the three   taps  provided   one on   the inlet manifold,one  on   the  cylinder block above  the starter motor  andthe other   at   the   base  of the   radiator.

    Take  off the   bonnet,   as   detailed   under Section   D.2,and the radiator  steady   rods   ;   this  will provide plentyof clearance.   Next   remove the  bonnet  sides as detailedunder   Section   R.14.

    Remove   the   air   silencer,   fume   extractor   pipe,distributor   head   and   ignition   harness   together   with

    the  aluminium   casting   forming   the  air   intake betweenthe  two   carburetters.

    Detach  the   throttle  control   rod   slow-running   cable,and   the mixture   control   cable.   Disconnect   the   fuel

    line   at   the   T-piece   between   the   two   float-chambersand   remove   the   carburetters.   Do   not   disturb   theinterconnecting   rod between  the  two throttles.

    Take   off the inlet   manifold, noting   the two rubberwashers   between   the   manifold  and   the  cylinder   head.These   washers   should   be   renewed   each   time thecylinder   head   is   removed.

    Disconnect   the   two   water   hose   connections,   oneat   the thermostat   and   the other   at   the   water pump

    inlet.   Then   unscrew   the water   temperature   controlunit.

    Remove   the  fan  and   water pump   belts   (see  SectionsA. 16   and A.28),  and  disconnect the  exhaust  pipe  at  themanifold.

    Disconnect   the rubber   hose   between   the waterpump   and   the   cross-flow   pipe   and   then   take   off thelatter   before   removing   the  exhaust   manifold.

    Next,  take   out the sparking  plugs  and   remove   bothrocker  covers.

    Remove   all   the  push-rods   by  seeing   that  each   valveis   closed, and then   depressing the  spring   with  a   lever,at the  same   time  moving   the rocker to one  side.   Mark

    the   push-rods   so   that they   can   be   replaced   in   thepositions   from which   they were   removed.

    Slacken each  cylinder  head  holding-down nut  a  slight

    amount   and   then   remove them   all.   Lift off the   headand   the  gasket.

    The   cylinder   head   is  now   ready   for   decarbonisation2nd valve grinding, as detailed  in Sections A.26 and A.27.

    A.6

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    (2{   LITRE)TUE   ENGINE  A

    Replacement  of the   head   is   a   reversal  of the  aboveprocess,  but the  holding-down nuts  must  be tighteneddown gradually   in the sequence  shown   in the  diagramFig.  A.7.

    ~I2K   Fig.   A.7.Sequence   fortightening thecylinder   head

    stud   nuts.

    If   a   torque   spanner   is   used,   the  correct tighteningfigure   is   900   in./lb.   (10.35   m./kg.).

    On   some   earlier cylinder   heads   the   brass   insertin   the   upper transfer  port of the hot   spot  is   a   loosefit.   The   open   side  of the   insert   must   always   face  thefront  of the  engine.

    The baffle tube   fitted  across  the   head and  inside  the

    lower port   is   renewable.

    Section   A.II

    REMOVAL   OF   PISTON   AND

    CONNECTING   ROD

    The big-end   will   not   pass   up   the   cylinder   bore,neither   will   the   piston   pass   the   crankshaft.

    The   procedure,   when   it   is   desired   to   remove   thepiston   and   connecting   rod  assemblies,   is   as  follows

    Remove the cylinder  head as detailed  in Section A.7.

    Drain  the engine  sump  as   explained  in  Section A.l.Remove   the   sump as   detailed   in Section  A.2.Take   out  the split   pins  and   remove   the  castellated

    nuts   from   the   big-end   bearing bolts.   Take   off   thebearing   cap,   which   is   marked   to   line   up   with   theconnecting   rod.   Remove   the   fixing   bolts   and   push   the

    connecting   rod  up   the cylinder  bore   until the gudgeonpin   isiust  clear  of the  top   face  of the   block.

    Remove   a   circlip   and   tap out the   gudgeon   pinwith   a  drift,  taking   care   to   support   the   piston   at   thesame time,  otherwise the  connecting rod   may be   bent.The   piston   can   then   be   withdrawn   upwards from   the

    cylinder,   and  the connecting  rod downwards   throughthe  crankcase.When   refitting   the   pistons   to the   bores,   use   some

    form   of  piston   ring   compressor   in   order to   prevent

    ring  damage.

    Section   A.9

    REMOVAL   AND   REPLACEMENT OF THEPISTON   RINGS

    If   no   special   piston   ring   remover   is   available,   usea  piece  of thin  steel  such   as   a  suitably  ground   hacksawblade,   or  disused   ~020in.   (.50   mm.)   feeler   gauge.

    Raise  one end  of the  ring,   and  insert   the  steel   stripbetween ring  and   piston.   Rotate   the strip   round thepiston,  applying   slight   upward   pressure   to the   raised

    portion of the   ring,   until   it   rests   on   the   land   abovethe  ring   groove.   It  can   then  be   eased  off the piston.

    Do not  remove   the  piston  rings  downwards  over theskirt of the   piston.

    Before   fitting   new   piston   rings   the grooves   in thepiston   must   be   scraped clean   of   any   carbon deposit,taking   care   not to   remove   any   metal,   since   playbetween the  ring  and the groove  reduces gas   tightnessand   produces   a   pumping   action   leading   to   excessiveoil   consumption. There  must   be   no   play between   the

    rings and   their grooves   but they must  nevertheless  befree to   move   without   restriction.

    Important.—New  rings  should  be  tested  in   thecylinder bore   in order   to   check  for   correct  clearance at   the ends.

    To do   this   effectively   the   piston   should   be    inserted 

    approximately    I   in.   (2.5  cm.)   down    the   cylinder   and each ring   then  pushed  down  on   to   the top   of the piston  and held  there in order   to   keep  the  ring   square  with   the  bore.

    The   end   gap   should   be   between   ~008in.   and   .012   in.(.2   mm.   and   ~3mm.).

    Fig.   A.8.

    Checking   the piston   ring gap.

    A.7

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    Riley   I{   and   2{   Litre.   Issue   2   (E) 78538—4/53   A.9

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    (2-b   LITRE)A   THE   ENGINESection   A.1O   Section   A.13

    FITTING   THE   GUDGEON   PINS   AND

    REASSEMBLING   THE   PISTON   AND

    CONNECTING   ROD

    The   piston   and   connecting   rod   are   replaced   bypartly   inserting   the   piston   in   the   cylinder   from   the

    top   and   introducing   the   connecting rod upwardsfrom   the   crankcase.   The   two   are   then   coupledtogether   by   the  gudgeon   pin.

    The   gudgeon   pin   is   a   push   fit   in   the little-end   and

    a   light   drive   fit   in the   piston   at   room   temperauire.Gudgeon   pins  ~002in.   oversize   (Part   No.   166516)   areavailable and   may   be   fitted   to   take   up   slack   in thesmall end   bushes   or   pistons,   which   must   of   course

    be   reamed   out   to   suit.   The   gudgeon   pin   circlipsshould  be fitted with   a  special   pair of peg-nosed   pliers.

    Take   care   when   tapping   the   gudgeon   pin   intoposition   in the  piston   to support the  piston adequately

    so as  not to damage  it  or the connecting rod.

    Section   A.11

    REMOVAL   AND   REPLACEMENT   OF   THECARBURETTERS

    Detach   the forward   end  of the   bonnet   release   rodand   then  take  off the   bonnet  side  by undoing   the nutand   bolt   at   the forward end and the two screws at therear.   See   Section   R.14.

    Take   off the   ignition   harness   and   remove   the   airsilencer.   Remove   the   cast   aluminium   air   intakebetween   the   carburetters.   The   forward   end   is   heldby set   screws,  the  rear  by  nuts  and   studs.

    Disconnect the  fuel   line  at   the  T-piece  between  thefloat-chambers   and   detach   the   rich   mixture   control

    cable  from both carburetters.Remove   the   throttle   control   rod   from   the   rearcarburetter and   undo   the set   screws  holding the   handthrottle   cable   at   the   quadrant.   Undo   the four   nutsand   take  off the  carburetters.

    Section   A.12

    REMOVAL   OF   THE   INLET   MANIFOLD

    Remove   the carburetters   as detailed   in   Section A.l  I .Drain   the   cooling   system   by   means   of the three

    drain   taps   (see   Section  A.7).

    Undo the   six nuts   holding   the   manifold   in  positionand then  withdraw the  casting  over the  studs.

    Renew   the  two   rubber   sealing   washers, and   whenreplacing   make   quite   sure   the   open end   of the   brassferrule   in   the   cylinder   head   is   pointing   forward.

    REMOVAL  OF THE   EXHAUST   MANIFOLD

    Drain   the  cooling   system and   remove   the  coolingwater inlet   pipe.   Disconnect   the   exhaust pipe   at   themanifold,   undo   the   retaining nuts,   and   then   take   offthe  manifold.

    Section   A.14

    REMOVAL   AND   DISMANTLING   OF   THEWATER   PUMP

    To   detach   the  pump,  the dynamo  and  fan   belts   mustbe   removed   by   slackening   back   both   adjustments.See   Section   A.28   for the  fan   and   Section   A.16   for  thedynamo.

    It   is   not  necessary   to   remove   the   pump   body  from

    the   cylinder   head   because   the   bearing   housing   com-plete   with   pulley   and   impeller   may   be   taken   out   byremoving   four set  screws   and washers.   Note   that  onescrew   breaks   into the   waterway,   and  when   refitting,a   copper washer   is   necessary  under the  screw   head.

    Fig.   A.9.

    The water   pump   partially   dismantled.

    If the   pump   body   and   thermostat   are   separated,

    note the rubber ring and  adaptor between  the thermo-stat  housing   and   the   pump   body  which   forms   the   by-

    pass   port.   The   rubber  ring,   between  the  water  outletelbow   and   the   cylinder   head   itself, should   also benoted.   These   rubber  rings must   be   in good   conditionand   should   be   renewed   if any   doubt   exists  as  to   theirserviceability.

    A. 10   Riley   1+   and   2~   Litre.   Issue   2   (E) 78538—4/53

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    (2+   LITRE)   TIlE   ENGINE  ATo   dismantle the  pump, take  off the brass   Simmonds

    nut   holding   the   impeller, draw   off the   impeller   andextract   the   Woodruff   key.

    Lift   off   the   spring,   the   collar,   the rubber   seal   andthe  carbon   disc and then  take   out the driving  peg forthe  carbon   disc.   If the rubber seal   is   at   all   swollen   itmust   be   renewed,   otherwise   water   circulation   maybe   impeded   and   the engine   tend   to  overheat.

    Next lift off the   sealing   plate   and   remove   the

    Simmonds   nut  at  the other  end  of the  shaft.   Draw offthe  driving   pulley,   which   is   held   by   a  Woodruff  key.There   is   a   felt   washer   behind   the   pulley   which   mustbe   taken   off if   it   remains   on   the   pump   body   before

    the shaft   is   pressect  out  towards  the  rear  ofthe pump.The shaft  will  come out  with  the  rear  lipped  oil   seal

    and   packing   ring,   together   with   the   ball bearings,inner  distance   tube   and   the   inner   race  and   rollers   ofthe front  bearing.   The   outer race  of the front  bearing

    Section   A.15SETTING   THE   TAPPETS

    Remove   the ignition   harness   and   the   small   inter-connecting   breather   pipe   from   the rocker   covers.Take off   the rocker   covers   and   this   will   expose   therockers  and   their   adjusters.

    The   tappets  are   set   by   slackening   back   the   locknutand   screwing the   ball-ended   adjuster   in   or   out   asrequired.   Set  the   clearance   to   .003  in.   (.08   mm.) inletand   .004   in.   (.10   mm.)  exhaust   with  the  engine  hot.

    is   pressed   into the housing from   the rear.   The distance-piece   between   the  outer  races  can   be   lifted   out. If   itis   necessary   to   remove   the   outer   race   of the   frontbearing   this   can   be   accomplished   by   levering   it   outwith   a   thin   screwdriver   blade.

    When   reassembling   the bearing  and pulley   assemblyto   its   housing,   note   that the lower set screw   on   theleft-hand   side   (facing   forward)   has   a   copper   washer,because this   hole   breaks   into   a  water  passage.

    Section   A.16

    REMOVAL   OF   THE   DYNAMO   BELT

    Remove   the   fan   belt   by   releasing   the   fan   spindleclamp  bolt   and   moving   the spindle towards   the   pump

    pulley, then   slacken  the  dynamo   belt   by   releasing   thethree   dynamo   attachment   bolts   and   moving   thedynamo  towards   the  engine.

    Rotate   the   fan   pulley   to   its   lowest position   by

    Fig.   A.lO.This   is a  section  of  the   water pump,   whilst   inset showsthe modification   to   the   water   seal   on later   pumps.

    A. II

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    A.13

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    (24   LITRE)A   THE   ENGINF

    Fig.  A.I   I.

    The   method   of removing the   dynamo   belt   by   undoingbolts A   and B.

    slackening   the pinch   bolt   and using   a   small   bar   in theholes provided.

    To   save   jacking   up   the  engine, remove   one   enginemounting   bolt   at   a   time   on   the   dynamo   side   of theengine.   This  will  allow the  belt to  slip   past the  mount-ing.   Note   that   one   bolt   carries   the   dynamo   steadyarm and the other   a   distance-piece.

    Section   A.17

    REMOVAL OF   THE   CRANKSHAFT

    PULLEY

    Take  out  the bolt through the   pulley   and   its   fixingnut.   Unscrew the  nut,  which  has   a’ right-hand thread,and   withdraw the   pulley,   which   is   on   a   parallel   shaftwith a  Woodruff key.

    Section   A.18

    REMOVAL OF THE   TIMING CHAIN   COVER

    Remove   the  dynamo   belt   and   crankshaft   pulley   as

    indicated   in Sections A.16   and  A.17.There   are   fifteen nuts   and   spring   washers   holding

    the timing  cover   to the  block   and   in addition   there  isone  set screw  at   the  bottom which  secures   the  sump.

    Also,   between   the  engine   mounting   and   the  dynamothere   is   a countersunk   screw.

    There   is   a   Simmonds   nut,   a   steel   washer and   a  corkdisc   in the centre  of the cover which  must  be   removed.The  cover  can   then   be   lifted   off and   there   is   no  gasketat  this   joint.

    Note   the   position  of   the   oil   return   ring   and   the oilthrower   ;   the latter   has   the   dished   portion   towardsthe  engine.

    Section   A.19

    REMOVAL   OF   THE   CRANKSHAFT   CHAIN

    WHEEL

    Remove   the   dynamo   belt,   crankshaft   puijey   andtiming  cover  as   indicated   in Sections   A.16  to  A.18.

    Remove the timing chain  as  explained in Section  A.20and draw off the wheel, which is   on   a parallel shaft witha  Woodruff   key,  using   a   suitable   extractor,  ST.58,   toavoid damage.

    Section   A.20

    REMOVAL   AND   REPLACEMENT   OF   THE

    TIMING   CHAINTake   off the timing   cover   and   crankshaft   puliey.

    Then wedge   the   tensioner   wheel   in   its   extreme

    Fig.   A.12.This   illustration  shows   the tensioner wedge  and   the camshaft

    bush which   is  partially withdrawn  from the   crankcase.

    A.14

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    (2+  LITRE) -THE  ENGINE Aposition,   with  the   ratchets   removed,  so that the  chainfalls slack.   Undo   the   lock   washer   and   set   screwholding   one   of the   camshaft chain wheels   and   thenwithdraw the wheel.   The chain   may then   be   lifted   off.Although  the   chain wheels   are   marked   for   timing,   itis   a   wise   plan   to   polish   two   of the   chain   links   to

    correspond   with   marks   scribed   on   each chain   wheelthis   will   considerably   help   chain   refitting. If a   newchain   is   to   be used,   mark   the   old one   and   use   it   asa  guide   for the  new.

    Before   marking   the  old   chain,   first   make   sure   it   isnot   already   marked,   to   avoid confusion.   Remember

    that the   marked   chain   links   only   coincide   with   themarked   teeth   of the   chain wheels   once   in   every104   revolutions of the crankshaft.

    Fig.   A.13.The setting   ofthe   crankshaft   and   camshafts for  correct valvetiming. Notethe  keyway onthe crankshaft,   the timing marks

    on the  camshaft   sprockets  and   the   marked   chain   links.

    Section   A.21

    REMOVAL   OF   THE   CHAIN   TENSIONER

    Remove   the   dynamo   belt,   crankshaft   pulley   andtiming   cover   as   explained   in Sections   A.16   to   A.18.Take   off the   ratchet portion   of the   tensioner   andwithdraw the   wheel,   taking   care   not to   lose   thespring.   The square  stub   upon   which   the   wheel slides

    is   held   to the   cylinder   block   by  countersunk   screws.One   of the   ratchet   plates   on   the   adjuster   is   pro-

    vided   with  slotted   holes   so  that   when   the   tension   of

    the timing   chain   is   set   the   plungers   are   located   sothat while  one   is   at   the   bottom   of the   ratchet   tooththe other   rests   on   the top of   a   tooth   on   the   otherplate.   Thus   the slightest amount  of wear   in the  chainwill   be   taken   up   immediately.

    Section   A.22

    REMOVAL   OF   THE   CAMSHAFTS

    Take  off the   engine   pulley,   timing   cover  and   timingchain as described  under Sections A.16,   A.18,  and A.20.Remove   the cylinder   head as   indicated   in  Section  A.7.

    Lift  out the tappets from   the top,   making sure   thateach  is   marked   for  subsequent   reassembly in the sameposition.

    Remove   the   camshaft   chain   wheels   as   indicated   inSection   A.20.

    With   the   chain   wheels   removed,   undo   the   set

    screws   which   hold   the   camshaft   and   front   bearingassembly  to the   block   (see   Fig.   A.12). The camshaftis   then   ready   for  removal.   In   the  case   ofthe  exhaustcamshaft  the   distributor   must   first   be   removed   (seeSection  C.7).

    Section A.23

    REMOVAL   OF   THE   ROCKER   GEAR

    Take   off the ignition   harness   and   remove   -thebreather   pipe   and   rocker covers.

    Depress   each   valve in   turn,   move   the   rocker   aside

    and  extract   the  push-rods.   Undo  all   the securing  nutsfor   the rocker   pedestals   and   lift the   assembly awaycom plete.

    The   rockers   are   bushed   and   of   two types, left-handand   right-hand.   Each   rocker-shaft   is   in   four   sections

    carried   in   five   pedestals,   the   sections   being locatedby  set  screws  on   the  second   and fourth   pedestals,  thefront   and   rear of which   are   not   Interchangeable witheach  other or side for side.   They  are drilled  for rockerlubrication, the oil  passing up  a  hollow  stud. Note thatflats   are   machined   on   the   rocker-shafts.   These flatsmust  face towards   the  valves.

    Section A.24

    REMOVAL   OF   THE VALVES

    The   valve   springs   are   retained   in   position   on   thevalves   by  means   of   a  collar  and   two split   collets.

    Fig.   A.14.

    Valve   spring   compressor.

     A.15

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    A   THE   ENGINESupport the  head  ofthe  valve  inside   the combustionchamber, apply a   suitable compressor to   compress   the

    spring   and   cap,   and   the   collets   may   be   removed.The valve springs are  not  of constant  pitch   and  must  berefitted  with   the   close-coiled   end at   the  bottom.

    Section A.25

    REMOVAL   AND   REFITTING   OF   THE

    VALVE   GUIDES

    The   valve   guides   are   interchangeable   and   quite

    plain,  without  any shoulder. They  may be   tapped   outwith  a  drift,  and   when  fitting a  replacement guide thenew one   should   be   pressed   in   until   the   top   is   j~ in.(20.64   mm.)   above   the spring  seat for   both   inlet  andexhaust. The extra   length  of the  exhaust  valve guideshould  project   into  the  valve port.

    Fig.   A.15.

    A special   tool   may   be  made   for   fitting the   valve guidescorrectly.

    Section   A.26

    DECARBONISING

    Remove   the   cylinder   head   as   explained   in   Section A.7.

    Take   out the   valves   as   indicated   in Section   A.24.Lift off the  cylinder head   gasket,   and  plug all  water

    holes  and  the tappet  guides  with   cloth  plugs.Scrape   the   carbon   off   the   piston crowns,  cylinder

    heads  and   inlet  and   exhaust ports.   Take care   that   thepistons   are   not  scratched   by the   use   of   a  sharp tool.

    It   is   also  advisable   to   polish   the  combustion   chambers with   emery  cloth,   but   great   care   must   be   taken   toclean  away   all   traces of   abrasive  dust.

    Never  use  emery   cloth   on   the   piston   tops   because

    small   abrasive   particles   will   undoubtedly   find   theirway   into the  cylinder   bores.

    A  ring of   carbon   should   be   left on   the  periphery ofthe  piston crowns  by placing  a  piston   ring  on   the   top,and   the   carbon   round the top   of   the  cylinder   boresshould   also   be   retained  intact.

    Remove   all   traces  of   dust   by   means   of  compressedair   and   then   clean   well   with   paraffin. Always   use   anew cylinder   head   gasket   after   decarbonising.

    Section   A.27

    GRINDING   AND   TESTING   THE   VALVES

    AND   THEIR   SEATINGS

    Remove   the   valves   and   springs   as   detailed   inSection  A.24.

    Clean   each   valve  carefully  and   examine  the   seatingfor signs of pitting. If pitting is apparent then   the valvemust   be   refaced. The   same  applies   to the  valve   seats

    and  great care   must   be   taken   not to  remove   too   muchmetal.

    Fig.   A.17.

    The numbering   of the   valves  is  shown   in this  illustration.

    (2+   LITRE)

    Fig.   A.16.

    Removing   the   carbon.

     A.16

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    THE   ENGINE AEach   valve   must  be   replaced   in   the  same   port   from

    which   it   was   removed,  and  when   grinding   in   the facesa   fine   or   medium   grade   carborundum   paste   shouldbe   used.

    Place  a   light  coil   spring  under the  head  of the  valveand   use   a   suction-type   grinding   tool to   impart   areciprocating   motion   to the   valve.

    An  even   matt finish   is desirable, and  if the seat is   toowide   it   should   be   reduced   to  approximately   080   in.(2   mm.)   by  means   of   a   450   cutter.

    After   having   ground   in   each   valve,   the   ports,seatings   and   valve   itself   should   be   carefully   cleanedwith  paraffin   and   then  dried,   taking care   that  no   trace

    of grinding   paste   finds   its way   into the valve  guides.

    Section   A.28

    ADJUSTING   THE FAN   BELT

    The   fan belt  tension   is  altered   by slackening back thefan spindle pinch bolt and   rotating the fan  hub assemblycompletely   round   in   the   engine   mounting   bracketby means  of a  bar inserted   in   the holes  on   the  hub.

    #/

    Fig   A.18.

    The fan   belt adiustment.

    Section   A  29

    TO   DISMANTLE   THE FAN   ASSEMBLY

    Undo  the   pinch  bolt  holding   the   fan   hub assemblyto the   engine   mounting bracket   and   remove   theassembly  complete.

    Remove   the fan blades.Unscrew  the   lock-ring  at   the   rear   end   and   tap   out

    the   shaft   complete   with   rear   bearing, distance   tubeand the  front  bearing.

    The   outer   race   of the   front   bearings   stays   in   thehub   and   is   prevented   from   moving   towards the   frontend   by   means   of   a   distance   tube   between this   outerrace and   the  fan  end   plate.

    The   locking   ring  at   the   rear  end   carries   an   oil   seal.When   reassembling  take  care   that the  rollers  of the

    front   bearing enter the  outer   race squarely,   otherwiseassembly   will   not  be   possible.

    Section   A.30

    REMOVAL   AND   REPLACEMENT   OF

    THE   ENGINE   AND   GEARBOXDisconnect   the   battery.Drain   the   cooling   system   as  described   in   Section

    D.l.Remove   the  bonnet tops   (Section D.2)   and  sides  as

    explained   under   Section   R.l-4.Disconnect   the water   temperature   unit   at   the

    thermostat   and   remove   the   radiator   stays.Ren~ove   the   radiator   and   shell   as   explained   under

    Section   D.2.

    Disconnect the cable from   the coil   to the distributorand   remove the   coil   from   the  frame.

    Remove   the wire   stay  between

      the  frame

      andforward   engine   mounting.

    Take  off the air   filter  and  carburetters   as   explainedin   Section   A.l  I.   Take  off the   cables   to the   dynamoand   starter motor   and   disconnect   the   exhaust   pipeat   the  manifold.   Then remove   the  dipstick.

    Slacken   the   dynamo   adjusting bolts   and   push   the

    instrument   inwards   and   place   a   single   rope slingaround   the   middle   of the  engine. Then   take   off   themounting plate   on   the front of the   engine and   thebracket shown   in Fig. A.19.

    (2{   LITRE)

    Fig.   A.19.

    Method   of  removing the mounting.

    A. 17

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    (2+   LITRE)A   THE   EN1~lWUnscrew   the   union   on   the   oil   pressure   gauge   line

    and   uncouple   the   throttle   control   rod   at   the   bellcrank   on   the  side   of the   block.

    Slide   both  front   seats   right   back and   remove themfrom   the  car.   Then remove   the carpets  and   unscrewthe   knob   on   the   gear   lever.

    Remove   the   gearbox   cowl by   sliding   back   theforward   catches   and unscrewing   the  small   plate at   therear.   Then   take   up   the floorboards.

    Disconnect  the front   end  of the  intermediate   driveshaft  and   unscrew   the   reversing   light   cables  from   theswitch   unit   on   top   of the   gearbox.   Remove   thespeedometer   drive   gear   from   the  gearbox   and   undo

    the nut on   the wire   stay.

    Fig.   A.20.

    The method   of  disconnecting   the intermediate   shaft.

    Extract   the   pin   on   the   clutch   cross-shaft universal joint   and   then   remove   the   gear   lever   complete   bylifting out the spring   ring in  the gear lever  ball  housing

    and   the   two set   screws at   either   side.   When   liftingthe  lever   out, take  care   not to   lose   the  small   spring-

    loaded   ball   in   the   crank.Take out the  rear mounting  bolts under the gearbox

    and   then   the  complete gearbox  and   engine   unit   maybe   tilted  downwards  and  drawn   out  to the  front.

    Assembly   is   a  reversal  of this  process,   but note thatthe thick rubber  buffers   under   the   radiator   must   beabove the  mounting and  the thin  ones  below.   Tightenthe. Simmonds  nuts  sufficiently   to   just nip   the rubber.

    Tighten the  unit   mounting bolts fully and seethatthesteady cables at   the front   and  rear  are   just   in  tension.

    Section   A.31

    REMOVAL OF   THE   CLUTCH

    Take   off the   gearbox   as   described   in   Section   F.l.Slacken   back   the   retaining   screws   holding   the

    clutch  cover-plate   to the  flywheel.   The screws  shouldbe   undone   evenly   a   turn   at   a   time   and   diagonallyto   prevent   the   spring pressure   straining   the   clutchcover-plate.

    Fig.   A.21.

    The  method   of lining up the clutch  when   refitting  it   tothe flywheel.

    Section   A.32REMOVAL   OF   THE FLYWHEEL

    Take   off the   gearbox   as   explained   in   Section   F.l.Detach   the clutch   as   in Section   A.31.Bend   back   the   locking   tabs   and   unscrew   the  eight

    fitted   bolts.   The   flywheel,   complete   with   cast-ironfriction   face,   may then   be   either   drawn  or   tapped   offits   spigot   on   the   crankshaft.

    Fig.   A.22.

    The   flywheel   run-out   should   not   exceed   .004   in.   (.1   mm.).

    7)~

    A.20

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    (2+   LITRE)   THE   ENGINE ASection A.33

    REMOVAL   OF   THE   CRANKSHAFT

    Take   out   the  engine   unit   as   described   in   Section

    A.30.Drain  and  remove   the  sump  as   indicated   in Sections

    A.l   and  A.2.

    Take  off the  gearbox.   (See   Section   F. I.)Remove   the   clutch   and   flywheel   as   described   in

    Sections A.3   I   and   A.32.Disconnect   the   connecting   rods   from   the   crank-

    shaft.   (See   Section   A.8.)

    Remove   the   crankshaft   pulley.   (See   Section   A.17.)Take   off the timing  chain  cover   (Section   A.18)   and

    remove   the timing   chain   (Section   A.20).Take   out the split   pins   from   the   main   bearing   cap

    nuts and   undo   the  nuts.

    Lift off the   bearing   caps,   noting   that they   are

    marked   for   subsequent   correct  assembly,   and   detachthe split  sealing   plate  at   the rear.   This  is   held   by twolong  screws   with   tapered   heads.

    Lift out the  crankshaft.

    Section A.34

    OIL   PRESSURE

    Under   normal   running conditions   the  oil   pressureshould   not  drop   below   40   lb./sq.   in.   (2.8   kg./cm.

    2)  on

    the  gauge,   whilst  approximately   12   lb./sq. in.   (.9  kg.!cm.2)   should   be   shown  when  the  engine   is   idling.

    Should   there   be   a   noticeable   lack   of  pressure,   thefollowing   points   should   be   checked   over

    I.   That   there  is   a   good   supply  of the correct gradeof oil   in the  engine   sump.

    2.   That   the   pump   gears  are in   order  and   have  thecorrect   clearances.   (See   Section  A.4.)

    3.   That   the   gauze  oil   pump   filter is   clean and   notchoked   with  sludge.

    4.   That   the  bearings  on   the  delivery  side   to   whichoil   is   fed   under   pressure   have   the correctworking   clearances.   Should   the   bearings   be

    worn  and   the   clearances   excessive,   the   oil   willescape   more   readily   from   the   sides   of thebearings,   particularly   when   the oil   is   warm

    and fluid.   This   will  cause a drop   in the pressurerecorded   on   the   gauge,   as   compared   with   thatshown   when  the  bearings   are in good   order.

    Note.—.The   automatic   release   valve   deals   with   any excessive oil  pressure  when  the  engine   and  oil  are  cold.

    Cold   •running    and unnecessary   use    of   the   mixturecontrol   are  often   the cause  of  serious  oil dilution  by   fuel,and   of a   consequent  drop   in   pressure.

    New   engines   with   new   oil   will   produce   considerably higher  pressure   readings than   those   given.

    Particular    attention   is    called    to    the   recommended change   of  oil   every   3,000   miles   (5000   km.).   This   is   a most   important   factor   in  attaining   long  and trouble-free service   from   the   engine.

    Section   A.35

    REGRINDING   THE   CRANKSHAFT

    Crankshafts   are   provided   either   .020   in.(—.50   mm.)   or   —~040   in.   (—1.1   mm.) undersize   on

    the   main bearings   with   standard   size   big-ends   and

     —~020   in.   (—.50   mm.)   or   —.040   in.   (—1.1   mm.)undersize   on   the   main   bearings   with   either   .020   in.(—.50   mm.)   or   —~040 in.   (—1.1   mm.)   undersize   big-

    end bearing  journals.

    Section A.36

    LOCATING   TROUBLES

    Engine  will  not  start A. If the starter   will   not  turn   the  engine,  check   the

    following

    I.   Battery   discharged,  and/or   defective.

    2.   Disconnected   or  broken   leads.3.   Faulty   starter switch.4.   Faulty  starter motor.5.   Starter   cables shorting   to  earth.

    Fig.   A.23.

    The split   sealing   plate.

    Riley   1+   and   2~   Litre,   Issue   2 (E)   78538.—4/53   A.2  I

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     A.22   Riley   l{   and   2+   Litre.   Issue   2 (E)  78538—4/53

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    (2+   LITRE) THE ENGINE A6.   Battery terminals   badly   corroded   or   battery

    leads   loose.

    B.   If starter turns   engine   very slowly,   checkI.   Partly  discharged  battery.

    2.   Loose  terminals  or   connections.3.   Dirty or  corroded   connections.4.   Faulty  insulation   on   starter  cables.5.   Tightness   in engine.6.   Faulty   starter  brushes.

    C.   If starter turns  engine   smartly,   but it  will   not fire,check

    I.

    2.

    Plugs   not   sparking.

    Spark at   the  coil.   If the   coil   gives   a   goodspark,   check

    (a)   Gaps   in  plugs   too   wide   or   too close.

    (b)   Plugs oiled up.(c)   Plug   insulators   damaged,   or   excessively

    dirty.

    3.   If  poor   spark   at   coil,   check

    (a)    Low-tension or   high-tension   leads   from

    coil   to   distributor  loose   or  corroded.(b)   Distributor   points   dirty,   worn   or  out   of

    adjustment.

    (c)   Carbon   brush   not  making contact.(d)   Rotor   cracked.(e)   Faulty  condenser   (substitute a  condenser

    known   to   be   in   order).

    (f)   Faulty   coil   (substitute a   coil   known   tobe   in   order).

    4.   Check   the  carburetters   for fuel   supply.   If  nofuel   in the   float-chambers,   check(a)   Functioning  of the   fuel   pump.(b)   Air   leak   in   pipe   line,   indicated by rapid

    action  of the  pump.(c) Float-chamber   needles   sticking.

    5.   If fuel   is  reaching   the float-chambers,  check(a)   For   choked   jets.(b)   Water   in   the   fuel.(c)   Dirt   in   the   carburetters.

    (d)   Air   leak   in   induction   system.(e)   Check adjustment of carbu retter controls.

    If   engine  starts,   but   runs  erratically A.   Check  the following ignition  points

    I.   Loose   high-tension   leads   to   sparking   plugs.

    2.   Incorrect setting  of plug points.3.   Damaged   plug   or   moisture   on   plugs.

    4.   Loose   connection   on   battery   or   in   ignitioncircuit.

    5.   Faulty   high-tension   leads.6.   Battery  charge   low.

    7.   Battery   connections  faulty.8.   Defective  contact  breaker.9.   Defective  distributor.

    10.   Faulty  condenser.

    B.   Check   the following carburetter pointsI.   Water   in   float-chambers.

    2.   Choked   filters in   carburetters   or  fuel   pump,indicated by slow   pumping   of   fuel   pump.

    3.   Action of   fuel   pump.   Suspect   if  sluggish.4.   Jet   partially   choked.5.   Carburetter   or   carburetters

    indicated   by   sooty   exhaust.6.   Vents   on   fuel   tank   filler   caps   choked.7.   Obstruction   in fuel   feed  pipe.

    8.   Air   leak   into  induction   system.

    set   too   rich,

    C.   Check   the following   mechanical   points

    I.   Sticking  valves.2.   Incorrect   valve clearance.3.   Burnt  or  broken  valves.4.   Incorrect  valve   timing.5.   Incorrect ignition   timing.6.   Broken  or  weak  valve spring.

    7. Valve  guides  worn,  causing  air   leaks.8.   Cylinder  head  gasket   for leaks.9.   Back   pressure   due   to   damaged   exhaust

    system.

    lf   engine  starts  and  stops A.   Check   the  following   ignition   points

    I.   Loose   low-tension   leads.2.   Loose   distributor  clamp screw.3.   Faulty   ignition  switch   contact.

    B.   Check   the following carburetter pointsI.   Incorrect setting of carburetter  controls.

    2.   Blocked   fuel   pipe.3.   Water  in float-chambers.4.   Sticking.needle  valve.5.   Fuel   pump   failing   to   function regularly.6.   Air   leak   into fuel   line.7.   Fuel   level   low   in tank.

    If   engine  will  not   idle  or  run  slowly A. Check   the following carburetter points

    I.   Throttle stop  screws   incorrectly  set.

    2.   Hand   throttle   control   requires adjustment.3.   Throttle controls   incorrectly  set.4.   Weak   mixture or  over-rich   mixture.5.   Faulty   functioning of   fuel pump.

    A.23

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    A   TIlE   ENGINEB.   Check   the following mechanical   points

    I.   Sticking  valves.2.   Incorrect  valve   tappet  clearance.3.   Air   leak   in   induction   system.4.   Burnt   or   broken   valves,   indicated by   loss   of

    compression.5.   Broken   valve  spring.6.   Damaged   cylinder  head  or  gasket.

    C.   Check   the  following   ignition  pointsI.   Loose   high-tension   leads.

    2.   Incorrect  setting   of plug points.3.   Damaged   plugs  or  moisture   on   plugs.4.   Loose   connections   on   battery   or   in   ignition5.   Faulty   high-tension   leads.   [circuit.6.   Battery  charge   low.7.   Battery connections   faulty.8.   Defective   contact  breaker,  or  burnt   points.

    9.   Defective   distributor.10.   Defective condenser.

    Engine   fails   to   gi.ve  full  power A. Check   the  following   carburetter points

    I.   Faulty  or  insufficient   fuel  supply.2.   Air   leaks   in   induction   pipe   or  fuel   pipe.3.   Partly   choked   jet   or   jets.

    B.   Check   the  following   mechanical  points

    I.   Incorrect  valve   tappet  clearance.2.   Burnt  valve  or  badly  seating   valve.3.   ~Cylinderhead   stud  nuts  not tight.4.   Damaged   cylinder   head  gasket.5.   Valve   timing   incorrect.6.   Broken  or weak valve  spring.

    7.   Excessive carbon deposit.8.   Excessively  worn  pistons  and   cylinders.

    C.   Check   the  following ignition   pointsI.   Ignition   retarded too   far.

    2.   High-tension   leads  shorting,  or   loose.3.   Dirty sparking  plugs.4.   Sparking  plug   points   incorrectly  set.5.   Contact breaker points   incorrectly  set.6.   Contact breaker points  pitted.7.   Faulty  coil.8.   Faulty  condenser.9.   Low-tension connection   or   leads faulty.

    JO.   Battery  run   down or  faulty.

    Engine knocks A. Check   the following

    I.   Ignition   timing  too far   advanced.

    2.   Excessive  carbon   deposit.3.   Fuel   unsuitable  or  mixture  weak.4.   Loose  or  worn   bearings   or  pistons.5.   Defective or  unsuitable   plugs.6.   Valve   timing   incorrect   or   tappet   clearance

    incorrect.

    Engine   backfires A. Check   the  following   ignition  points

    I.   High-tension   cables   defective   or   connectionsloose.

    2.   High-tension   leads   incorrectly   fitted.

    3.   Low-tension   wiring   defective  or   connectionsloose.

    4.   Switch contact   faulty.5.   Distributor  gap  incorrect   or  points   pitted or

    dirty.6.   Contact breaker arm  sticking   or  defective.

    7.   Distributor  cover   cracked   or   loose.8.   Distributor   not   correctly   timed.

    9.   Rotor   carbon   brush   pick-up   defective   orworn.

    10.   Clearance  between   rotor   arm and   distributorstuds  excessive.

    II.   Coil   defective  or wet.12.   Defective condenser.13.   Plugs   overheated, unsuitable,   or   points   in-

    correctly  set.

    B.   Check   the   following carburation   pointsI.   Jets   choked   or   restricted.2.   Jets   incorrectly  set,   causing   weak   mixture.3.   Water   in fuel.

    4.   Choked   fuel   filters.5.   Inlet   manifold   joint   leaking,   or   manifold

    cracked.6.   Air   cleaner   passages  blocked.

    7.   Engine   running   temperature   too cold.8.   Throttle not  closing   completely   (indicated by

    engine   backfiring   when   proceeding  downhillwith throttle shut).

    C.   Check   the  following   mechanical   pointsI.   Valve timing  incorrect.

    2. Valve   tappet   clearance   incorrectly set.3.   Valve  sticking.4. Valve   seats  pitted  or   faulty..

    5.   Valve   spring  weak  or  broken.6.   Valve   guides   excessively   worn,   causing   air

    leaks.

    7.   Excessive  carbon  deposit.

    (2+   LITRE)

    A.24 

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    TIIF   ENGINE A

    PISTON   SIZES   AND   CYLINDER   BORES

    It   is   necessary   to   fit   new   pistons by   selectiveassembly,   and  to   facilitate this   the  pistons  are  markedon their crowns  with identification   figures which  mustcorrespond   with those  of the cylinders to   which   theyare   fitted.

    The actual   bore dimensions   of   each   cylinder   arestamped on   the  top   face  of the  cylinder   block   on   thefront   right-hand   corner   by the  appropriate symbol

    S.T.D.,   indicating   that the   cylinder   bore   is   ofstandard   diameter,   i.e.   possesses   an   actual   diameterof   3~l693   in.   (80.5   mm.).

    +0005,  indicating   that the  cylinder  bore   is oversizeto the   extent   of   -i-.0005   in.,   and   thus   possesses   anactual   dimension   of  3.1698   in.   (80.5125   mm.).

    +~00l,   indicating   that the cylinder  bore   is  oversizeto the   extent   of   -f-~00l   in.   and   thus   possesses   anactual   dimension   of   3~l703   in.   (80.525   mm.).

    ±~00l5,indicating  that the cylinder  bore   is oversizeto the   extent   of   +~00l5   in.   and   thus   possesses   anactual   dimension   of   3~l708   in.   (80.5375   mm.).

    The   pistons   are marked with   the   actualcylinder   bore size,   the   requisite   running   clear-

    ance  being   allowed   for   in   the  machining.Thus   those   marked   -V00l   in. should   be   fitted to

    bores marked   ~~00l   in.   and   so   on   throughout therange covered.

    When   the  cylinder  head   is   removed  and   the  pistonswithdrawn,   the   cylinder   bores should   be   measuredfor   wear,   Indication   that   a   rebore   of the   cylindersis   necessary   is   given   by   general   loss   of   performance,oiling   up,   and   poor  compression,   and   is  confirmed   bymeasurement   of the   bores.

    Rebores 

    Four   ranges   of   rebore   sizes   are   provided   andcylinders  must  only   be   rebored   to   one   of these  sizesto   ensure   the  supply  of the  correct   pistons.

    To   provide   the normal  machining tolerance, oversizepistons  are available   which   are   •0005   in.,   ~00l in.   and

    in• diameter   025   mm.  and   ~O375mm.)   largerThe   four   standard   oversizes   for   rebores   are

    +~0l0  in.   (.25   mm.)   [actualbore 3.1793 in. (80.75 mm.)]±~020in.   (.50   mm.)   [actualbore   3.1893   in.   (81   mm.)]+~030 in.   (.75   mm.)   [actualbore   3~ 1993 in.  (81  ~25mm.)]±~04Oin.  (1.00 mm.)   [actualbore 3~2093   in.(81.5 mm.)]and   oversize  pistons  are available   for the  above   rebore

    sizes   in   the following   range   H-0005   in.,   +~00l0   in.,+~00l5   in..

    There   are   thus   twenty   piston   sizes   available   forreplacement   purposes   as   tabulated.

    Piston  marking    Bore size 

    To  suit   3~l693   in.   to

    standard   bore   3.1697   in.

    To  suit   3.1698   in.   to

    +~0005   in. bore   3~l702   in.

    To  suit   3~l703   in. to

    ±~00l0in. bore   3.1707  in.

    To  suit   3~l708   in. to±~00l5in. bore   ‘3.1712 in.

    1st  Oversize  (±010in.)

    Piston  marking    Bore size 

    To   suit   3.1793   in.   to

    ±~0l0in. bore   3.1797  in.

    To   suit   3~l798   in.   to

    +~0l05  in. tore   3.1802   in.

    To   suit   3~l803   in.  to

    ±~0l10   in. bore   3.1807   in.

    To  suit   3~l808   in.  to

    ±0l Sin,   bore   3.1812   in.

    2nd   Oversize  (±~020in.)

    Piston  marking    Bore   size 

    To  suit   3~l893   in.   to

    ±~020in. bore   3~l897   in.

    To  suit   3.1898   in.   to

    ±~0205in. bore   3~l902   in.

    To  suit   3.1903   in.   to

    ±~02l0in. bore   3.1907   in.

    To  suit   3.1908   in.   to

    ±~02l5in. bore   3.1912   in.

    (2+   LITRE)

    Section A.37   Standard

     A.25

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    A   THE   ENGINF3rd Oversize  (+030 in.)

    Piston  marking    Bore   size 

    To   suit

    +~03O   in.   bore

    3~l993   in.   to

    31997   in.

    To   suit

    +~O305   in.   bore

    31998   in.   to

    3~2002   in.

    To   suit

    ±~O3lOin.   bore

    3~2OO3   in.   to

    3.2007   in.

    To suit

    ±‘0315in. bore

    3~20O8   in.   to

    3.2012   in.

    4th   Oversize   (+~04O   in.)

    Piston   marking    Bore   size 

    To suit

    +0400   in. bore

    3~2093   in.  to

    32097  in.

    To   suit

    ±~0405in. bore

    3.2098   in.  to

    32102  in.

    To   suit

    +~04l0   in. bore

    32103   in.  to

    32107  in.

    To  suit

    +~04l5   in. bore

    3~2l08   in.  to

    3.2112 in.

    (2+   LITRE)

    I.   ‘*-4+