TM   5-2815-241-34&P CYLINDER  BLOCK  -  CONTINUED ACTION LOCATION ITEM REMARKS REPAIR  -  CONTINUED NOTE Tool bit must rotate freely and clear counterbore ledge. 55. Cylinder block (1) Counterbore   (2) 58. Using  dial  indicator  depth  gage,  measure depth  of  counterbore  through  four  counter- bore  measuring  holes  on  ST-1064  adapter. The  average  of  the  four  readings  will be  the  present  depth  of  counterbore. ST-1059    counterbore tool  (3) a. Rotate  adjusting  nut  until  tool  bit  is resting  on  lowest  part  of  counterbore ledge and there is clearance between housing  (4)  and  adjusting  nut  (5). NOTE The  distance  between  housing  and  adjusting  nut  equals  amount  of  material  that  will  be removed  from  counterbore  ledge. b. Using a thickness gage of the same thickness  as  amount  of  material  needed to be removed from counterbore ledge (step  20)  rotate  adjusting  nut until  thickness  gage  is  just  held  between adjusting  nut  and  top  of  housing.  Tighten locking  nut  (8). c. Hold down on handle (7), applying more pressure on tool bit side, and rotate handle  in  a  clockwise  direction  until unit  turns  freely  and  is  bottomed  out between  adjusting  nut  and  top  of housing. d. Measure depth of counterbore as de- scribed  in  step  55. Compare  with  specifications  in step  18. 2-164