FUEL SYSTEM - N.12 removed.    The  gallery  should  now  be  cleaned  with  the aid of the special soft brass scraper (ET 071). Brush  all  carbon  from  the  nozzle tip using the brass wire    brush    contained    in    the    recommended    Nozzle Cleaning  Kit  shown  in  Fig.  N.14.    The  four  holes  in  the nozzle  tip  should  be  cleared  by  means  of  the  probing tool  (ET  120)  fitted  with  the  appropriate  sized  cleaning wire.    If  the  size  is  not  known,  it  can  be  ascertained  by careful trial of wires in the holes.  Extreme care must be taken,  however,  to  obviate  the  danger  of  wire  breaking off  in  the  hole,  as  its  removal  is  practically  impossible and renders the nozzle unusable. The cleaning wire should be fitted in the probe chuck so  that  there  is  approximately  1/16  in  protrusion,  thus giving  maximum  resistance  to  bending.    Enter  the  wire into the hole, pushing and rotating gently until each hole in turn is cleared.  Particular attention should be given to the nozzle needle seat.  This and the smaller cylindrical portion  above  it,  called  the  "stem"  and  "cone,"  can  he cleaned  with  the  fine  brass  wire  brush.    To  ensure  that the   stem   and   cone   in   the   nozzle   body   are   free   from carbon  particles,  the  soft  brass  stem  cleaner  (ET  072) should be applied with a rotary action pressing between the   fingers.      After   ensuring   that   the   exterior   of   the atomiser   nozzle   is   clean   and   free   from   carbon.      the nozzle   needle   and   nozzle   body   may   be   thoroughly washed   in   clean   fuel   oil,   or   an   approved   alternative, assembled  together  whilst  submerged  in  the  clean  oil and left immersed until it is intended to re-assemble the atomiser.      Should   it   be   desired   to   store   the   nozzle assembly  for  any  period  of  time,  then  the  needle  and nozzle should be lightly smeared with grease and stored away, preferably in a dust-proof drawer. The  atomiser  body  should  now  receive  attention,  it should   be   washed   in   clean   fuel   oil   or   an   approved alternative.    care  being  taken  to  ensure  that  the  highly ground face is clean and free from scratches.  This face must register with the atomiser nozzle flange cleanly and squarely    to    form    a    high    pressure    joint    and    must, therefore, be handled in such a way as to avoid damage to  the  surface.    The  exterior  of  the  atomiser  body,  of course, should be cleaned thoroughly. Re-Assembly of Atomisers The  atomiser  body  and  nozzle  assembly  may  now be    assembled    carefully,    after    having    immersed    the pressure   faces   of   each   in   clean   fuel   or   an   approved alternative,   to   ensure   that   these   faces   are   absolutely clean.    Place  the  atomiser  body  on  the  holding  plate, pressure  face  uppermost,  place  the  nozzle  assembly  in position (located by the dowel) and fit the nozzle cap nut, tighten  carefully.    Excessive  tightening  of  this  cap  may result in distortion of the nozzle and its consequent Fig. N.17.  Atomiser Testing Pump failure;   care   should   be   exercised   that   the   leverage applied  is  not  excessive.    Reverse  the  atomiser  on  the plate and refit the spindle, spring and spring cap (ensure that the steel shim washer is correctly located in the top of the cap).  Transfer the atomiser from the holding plate and  fit  to  the  Atomiser  Testing  Pump.    Pump  up  slowly until  fuel  spurts  out  of  the  four  nozzle  holes  and  whilst still pumping slowly turn the spring cap, using a suitable screwdriver,   in   a   clock-wise   direction   increasing   the spring  tension  until  the  breaking  pressure  is  that  quoted against Setting Pressure on Page B.12. The  atomiser  is  good  for  service  if,  as  previously mentioned.        when    the    Atomiser    Testing    Pump    is operated   at   approximately   twenty   strokes   per   minute, four  effective  and  even  sprays  breaking  into  a  very  fine mist are obtained. NOTE:    When  testing  atomisers  for  spray  formation, as opposed to setting the nozzle breaking pressure, always  isolate  the  pressure  gauge  by  means  of  the valve  fitted,  to  prevent  possible  damage  caused  by rapid fluctuations in pressure. Pressure Setting To   set   the   pressure   at   which   the   nozzle   should open,   slowly   move   the   hand   lever   downwards   and carefully   watch   the   pressure   gauge   for   the   highest recorded  pressure  before  the  needle  "flicks,"  indicating the needle lifting off its seat.  Any necessary adjustment is  effected  by  loosening  the  locknut  (3)  and  turning  the spring cap (4) clock-wise to increase or anti-clockwise to decrease   the   breaking   pressure.      Tighten   the   locknut and re-check the