NOTE Lift  cylinder  head  straight  up  until  it clears  the  two  dowel  pins  in  the  block; then  move  cylinder  head  to  the  left  to avoid  bending  the  fuel  injection  lines. Remove  the  cylinder  head  gasket. q.  Rocker  Arm  Shaft  Assembly  Disassembly. (1)   Refer   to   figure   14-37.   Remove   plug,   spring washer,  and  washer  from  each  end  of  the  rocker  arm shaft. (2)   Remove   shaft   locating   capscrew   and   lock- washer  in  the  top  of  the  rocker  arm  bracket  (third bracket   from   front   end). NOTE Replacement   brackets   will   all   contain threaded  hole  in  the  top  of  the  rocker arm   bracket. (3)   Slide   rocker   arms,   springs,   and   brackets from   the   rocker   arm   shaft. d.  Cylinder  Head  Assembly  Disassembly. (1)   Using   a   spring   compressing   tool,   remove spring   retainer   locks,   and   carefully   release   tension on  the  valve  spring. Remove   spring   retainer   and valve   spring. See  figure  14-38. (2)  Place  valves  in  a  rack  as  they  are  removed from  cylinder  head  so  they  can  be  identified  and  re  - installed  in  their   original   locations. (3)  The  valve  guides  may  be  removed  by  pres- sing  them  out  through  the  top  of  the  cylinder  head. (4)   Remove   valve   seats   by   electrically   welding three   small   beads   on   inside   circumference   of   insert as   illustrated   in   figure   14-39.   Allow   insert   to   cool, then  lift  or  pry  out  with  a  bar. e.   Camshaft,   Camshaft   Gear,   and   Valve   Lifter Removal. (1)  Refer  to  para  14-72  and  remove  timing  gear cover. (2)  Refer  to  paras  14-18  and  14-21  and  remove the   overspeed   switch,   adapter   and   tachometer   drive. (3)   Before   removing   the   camshaft   from   the cylinder   block,   check   the   camshaft   gear   backlash. The  backlash  between  the  mating  gear’s  of  the  crank- shaft  and  the  camshaft  is  0.  0015  to  O.  0009  inch.  New parts  must  be  installed  when  the  backlash  between  any two   mating   gears   exceeds   0.015   inch.   The   backlash between  hydraulic  pump  gear  and  camshaft  is  0.003 to  0.011  inch. (4)   Remove   capscrew   and   washer   securing   cam- shaft   gear   to   camshaft.   (See   fig.   14-35.   ) (5)  Before  the  camshaft  can  be  withdrawn  from the   cylinder   block,   the   valve   lifters   must   be   posi- tioned  so  that  they  do  not  interfere  with  the  camshaft lobes. (6)  With  the  engine  removed  from  the  unit  for overhaul,  simply  lay  the  cylinder  block  on  its  side and  push  the  valve  lifters  to  their  uppermost  position and   carefully   withdraw   the   camshaft. CAUTION Be  careful  that  the  camshaft  lobes  do  not scratch   or   mar   the   camshaft   bearings   as the  camshaft  is  withdrawn  from  the  cyl- inder   block. (7)  If  the  engine  is  mounted  in  a  unit,  the  valve lifters  can  be  held  in  their  uppermost  position  in  the following  manner. (a)   Make   up   twelve   pieces   approximately 16  inches  long  of  5/8  inch  wooden  dowel  rod  and  taper one  end  of  each  slightly. (b)  Insert  the  tapered  ends  of  the  dowels into  the  valve  lifters  (fig.  14-40)  into  the  holes  for  the push  rods  in  the  cylinder  block  and  force  each  one into  a  valve  lifter. (c)  Grasp  adjacent  dowels  for  a  set  of  ex- haust  and  intake  valves  carefully  pull  the  exhaust  and intake   valve   lifters   up   to   their   uppermost   position and  place  a  stout  rubber  band  around  the  two  adjacent dowels.   Repeat   for   each   set   of   valves. (8)   It   maybe   necessary   to   rotate   the   crankshaft so  that  the  connecting  rods  will  not  interfere  with  the camshaft   lobes   during   removal. (9)   After   removing,   the   camshaft   with   gear from  the  cylinder  block,  check  the  thrust  plate  clear  - ante  (end  play)  by  inserting  a  feeler  gauge  between the   thrust   plate   and   camshaft   journal.   The   end   play is  0.0027  to  O.  0083  inch.  If  the  end  play  exceeds  the maximum  wear  limit  of  O.  015  inch  with  a  new  thrust plate,   the   camshaft   gear   must   be   replaced. (10)  The  valve  lifters  may  now  be  removed  by removing   the   dowels. (11)  Place  the  camshaft  in  a  press  and  force  the camshaft   from   the   gear. This  is  necessary  due  to  the press   fit. Change   3   14-77