TM 10-3930-671-24 Several   good   makes   of   ridge   reamers   are   available which will ream the top of the bore in direct relation to the worn  area  so  that,  should  the  worn  area  be  off-center slightly, there will be no partial ridge remaining. 2. Drain the crankcase and remove the oil pan. 3. Remove  the  cap  screws  holding  the  connecting rod  caps  to  the  rod.    Keep  the  cap  and  bolts  in numerical  order  so  that  when  the  pistons  and rods  are  removed  from  the  engine,  the  cap  can be reassembled and kept with its mating part. 4. Push    the    pistons    and    connecting    rods    up through   the   top   of   the   cylinder,   carrying   with them all the carbon and metal chips left from the cleaning   and   ridge   reaming   operation.      When doing  this,  every  precaution  must  be  taken  to prevent  damage  to  cylinder  bores  by  the  sharp comers and rough edges of the connecting rods. 5. It    is    important    to    remove    the    glaze    on    the cylinder bores by using a  cylinder  hone,  with  an adjustable   stone   tension,   in   order   to   assure quick   seating   of   the   new   piston   rings.      If   the cylinder  glaze  is  not  removed,  you  will  have  no assurance   as   to   when   the   rings   will   begin   to function   properly   and   control   the    oil;    this    is especially true when chrome rings are used. The following step-by-step procedure Is recommended: a. To get the correct crosshatch pattern with a cylinder hone, use a top quality electric drill with a speed of 500 R.P.M.  or less and 280 grit stones. b. Cover   the   entire   crankshaft   with   a   clean, slightly  oily  cloth  to  prevent  abrasives  and dirt from getting on the crankshaft. c. Remove  the  excess  carbon  deposits  from the top of the cylinder wall before beginning the   glaze    breaking    operation    (this    is    to prevent loading the stones). d. Insert    hone    in    cylinder    and    expand    to cylinder  wall  with  slight  tension.    Using  a clean  brush,  wet  cylinder  wall  and  stones with kerosene.  Use a hand drill and surface hone   cylinder   with   a   rapid   up   and   down motion    to    produce    a    good    crosshatch pattern.    Apply  kerosene  continuously  and increase tension on hone adjustment until a good   pattern   and   finish   is   obtained.      A smooth,   bright   finish   of   10   to   15   micro inches (0.25 0.38 micro meters) is desired. The  honing  operation  will  produce  a  sharp  edge  at  the bottom  of  the  bores.    Upon  completion  of  the  honing operation,   remove   this   sharp   edge   with   a   piece    of number 500 emery cloth.  If this edge is not removed, it can cause shaving of the piston skirts. Removing Sharp Edge After Honing e. Clean  the  loose  abrasives  from  the  stones by using kerosene and a wire brush. IMPORTANT:      Stones   must   be   used   wet.      Keep applying  kerosene  during  honing  to  prevent  stones from   drying   out   and   causing   an   incorrect   honing pattern. f. The  most  desirable  cylinder  finish  is10-1  5 micro inches (0.25 -0.38 micro meters); with this  finish,  the  depressions  in  the  surface tend to keep a supply of lubrication between the mating parts: this finish can be obtained by using 280 grit stones on the hone. F-174