TM5-6115-593-34 NAVFAC P-8-631-34 TO-35C2-3-463-2 CAUTION Special   care   must   be   used   to   avoid breaking  carbide  tips.     Sharpen  tipped tools on a diamond-impregnated wheel. (15)  Remove    crosshead    guides    marked    for replacement using a dowel puller. (16)  Using   a   crosshead   guide   mandrel,   press new   guides   into   cylinder   head   to   obtain protrusion of 1.860 to 1.880 inch (47.24 to 47.75 mm). (17)  If     crosshead     guide     bore     is     worn     or mutilated,     install     oversized     guides     as follows: (a)   Drill guide bore in head to original depth with a 29/64-inch drill. (b)   Lubricate  and  ream  bore  with  a  15/32- inch reamer. (c)   Install oversized guide until guide protrusion    is    1.860    to    1.880    inches (47.24 to 47.75 mm). (18)  Remove  loose  or  excessively  worn   valve seat inserts by striking insert sharply with a chisel,  causing  it  to  crack  and  release  the press  fit.    Remove  all  inserts  if  head  has been resurfaced. CAUTION Cover the valve  seat  with  a  rag  to  avoid injury from broken pieces of the seat. (19)  Enlarge counterbore to next oversize using valve    seat    insert    cutter.        Inserts    are available   in   standard   and   oversizes   as tabulated in Chapter 1. NOTE If   head   was   resurfaced   and   standard inserts are to be used, deepen counterbore only. (20)  A  valve  seat  insert  tool  must  be  used  to hold and drive cutters. (21)   Cut  counterbore  0.006  to  0.010  inch  (0.15 to 0.25 mm) deeper than insert thickness to permit peening of head to hold insert.  It is important    to    allow    cutter    to    dwell    for several  revolutions  upon  reaching  proper depth   in   order   to   ensure   a   perfectly   flat surface at the bottom for the insert to seat on. (22)   Install  valve  seat  insert  and  peen  around insert  at  least  five  places  with  a  1/4  inch (6.35 mm) diameter round end punch. (23)   After checking condition of grinding equipment,     grind     valve     seats     holding seating motor as nearly vertical as possible. (24)   Check  valve  seat  which  should  be  1/16  to 1/8 inch (0.159 to 3.17 mm). (a)   If seating area (2, figure 13-44) is wider than   1/8   inch   (3.175   mm)   maximum, stock  can  be  removed  from  points  "A" and   "B"   with   specially   dressed   valve seat grinder stones. (b)   Narrowing   should   not   extend   beyond chamfer     on     seat     insert.          Chamfer provides for peening metal. Figure 13-44.  Valve Seat Insert, Cross Sections (25)  Dress wheel for final finish. 13-84