TM9-2815-202-34 (5) Valve inserts Inspect valve inserts for excessive wear, pitting, cracking, or improper seat angle. Replace inserts  as  follows: (a) (b) (c) Place cylinder head on wood blocks with bottom side up. Using valve seat insert remover (82), remove  valve  seat  insert  (83). Clean valve seat insert counterbore in cylinder head and inspect for concentricity,  flatness,  and  cracks. NOTE Insert  counterbore  has  a  diameter  of 1.2600 to 1.2610 inches and a depth of  0.3380  to  0.3520  inch. Counterbores must be concentric with valve  guides  within  0.003  inch  total indicator  reading. (d)    Immerse cylinder head in water heated to 180^oF-200^oF (82°C-93^oC) for 30 minutes  or  cool  insert  with  liquid nitrogen. NOTE Install  insert  in  cylinder  head  while head is still hot and insert is at room temperature or when insert is chilled and head is at room temperature. (e) Place cylinder head on a bench with bottom  side up. Place insert in (f) counterbore with valve seat side facing up. Using  valve  seat  insert  installer  (84), drive insert in place until it seats solidly in cylinder head. C  h  a  n  g  e      1_5-47