TM 10-3930-664-24 7. Inspect  valve  stem  tip for flatness.   If required, resurface valve stem tip. 8. Grind valve seat as follows: a. Install     valve     in     designated     bore     and measure valve depth (dimension D). Valve   depth   is   the   distance   from   valve face   to   head   deck.      Record   depth   and remove valve from bore. b. Grind    valve    seat    to    remove        scores, scratches,    and    burns.        Ensure    seat angles are maintained.  Intake angle must be 30 degrees.  Exhaust angle must be 45 degrees. c. Reinstall  valve  and  measure  valve  depth again.  Record depth as D1. d. Calculate         grind         depth         (GD)         by subtracting  dimension  D  from  dimension D1.         Grind   valve   seat   until   GD   equals 0.010 in (0.254 mm). D1 D = 0.010 inch (GD) e. Reinstall   valve   seat   and   measure   valve depth   again.      Depth   shall   be   0.0389   to 0.0598   in   (0.99   to   1.52   mm).      Replace valve if out of limits. f. Repeat  steps  a  through  e  for  remaining valves. 9. Apply  a  light  coat  of  lapping  compound  to  each valve.  Lap valves to companion seats. 10. Remove  valves.    Clean  lapping  compound  from valves and seats. 11. Measure  valve  seat  width  indicated   by   lapped surface  (dimensions  E  AND  F).    Width  E  shall not  exceed  0.060  in.    (1.5  mm).    Width  F  shall nor exceed 0.080 in.  (2.0 mm). 12. Grind areas G and H, as required, to center seat on  valve  face.    Grind  area  G  with  a  60  degree stone and area H with a 15 degree stone. 4-12