TM 10-3930-669-34 3-13. PISTON AND CONNECTING ROD ASSEMBLY REPLACEMENT/REPAIR (CONT). (7) Inspect cylinder liner as follows: NOTE If cylinder liner and or piston is worn beyond   limits,   replace   cylinder   and piston as a set. (a) Set  precision  gauge  to  3.937  in.  (100.000 mm). (b) Gauge   cylinder   bore   at   levels   i   to   4   of engine  centerline  "a"  as  well  as  crossline "b." (c) Compare readings with above dimensions. If not within plus 0.0079 in.  (0.2200 mm), replace cylinder and piston as a set. (8) Check  that  cylinder  top  and  bottom  joint  faces are flat.  Replace cylinders as needed. d. Assembly. NOTE Ring   gaps   should   be   positioned   at 90° intervals. (1) Install oil control ring (15) on piston (10). (2) Install  two  taper-faced  rings  (14)  on  piston  (10) with face marked "Top" toward top of piston. (3) Install  trapezoidal  ring  (13)  on  piston  (10)  with face marked "Top" toward top of piston. 3-70