TM 5-3895-382-24 2. Measure  the  depth  of  the  inlet  valve  and  the  exhaust valve  below  the  cylinder  head  face.    Use  the  gauge body (2) and the dial indicator (1) in order to measure the depth. Refer  to  Specifications,  "Cylinder  Head  Valve  for  the minimum, the maximum, and the service wear limits for the  valve  depth  below  the  cylinder  head  face.    The minimum and the maximum limits are dimensions for a new engine. Service  wear  occurs  on  an  engine  which  has  been  in operation.    If  the  valve  depth  below  the  cylinder  head face  on  a  used  engine  exceeds  the  specification  for service wear, the following Items must be replaced: valves valve inserts If  the  valve  depth  below  the  cylinder  head  face  on  a used engine exceeds the specification for service wear, the cylinder head may also need to be replaced. Testing The Valve Guides Perform this test in order to determine if a valve guide should be replaced. Illustration 71 Measure The Radial Movement Of The Valve In The Valve Guide. (1) Valve guide (2) Radial movement o the valve in the valve guide (3) Valve stem (4) Dial indicator (5)  When  the  valve  head  is  lifted,  the  edge  of  the  valve  head  is  the following value: 15.0 mm (0.60 inch) 1. Place a new valve in the valve guide. 2. Place a dial indicator with a magnetic base on the  face of the cylinder head. 3. Lift the edge of the valve head to a distance of 15.0 mm (0.60 inch). 4. Move the valve in a radial direction away from the dial indicator.    Make  sure  that  the  valve  moves  away  from the dial indicator as far as possible.  Position the contact point of the dial indicator on the edge of the valve head. Set  the  position  of  the  needle  of  the  dial  indicator  to zero. 5. Move  the  valve  in  a  radial  direction  toward  the  dial indicator   as   far   as   possible.      Note   the   distance   of movement which is indicated on the dial indicator.  If the distance is greater than the maximum clearance of the valve in the valve guide, replace the valve guide.  The maximum clearance is given in Specifications, "Cylinder Head Valves". Replacing Valve Guides and Valve Inserts Table 15 Tools Needed Valve Seat Cuter and 157-3720 Guide Reamer 1 NOTE: The  valve  seat  cutter  of  the  157-3720  Valve  Seat Cutter  and  Guide  Reamer  has  two  cutting  sides. One side is for cutting the valve seat in the valve insert for naturally aspirated engines which have 46   degree   valve   seats.      The   other   side   of   the cutter  is  for  cutting  the  valve  seat  in  the  valve insert  for  turbocharged  engines  which  have  31 degree valve seats. When  new  valve  guides  are  installed,  new  valves  and  new valve seat inserts must be installed.  Valve guides and valve seat  inserts  are  supplied  as  a  partially  finished  part.    The unfinished valve guides and unfinished valve seat inserts are installed  in  the  cylinder  head.    Then,  the  valve  guides  and valve inserts are cut and reamed in one operation with special tooling.  This procedure ensures the concentricity of the valve seat to the valve guide in order to create a seal that is gas tight NOTE: All lubricant must be removed from the outside of the   inlet   and   exhaust   valve   guides   before   the valve seal is installed. Perform  the  following  procedure  in  order  to  correctly  adjust new valve guides and valve insets: 1. Remove the original valve guide and the original valve seat insert.  Install a new valve guide and a new valve seat  insert.    Refer  to  the  Disassembly  and  Assembly manual for removal and installation procedures for valve guides and valve inserts. NOTE: Do not cut the valve seat before the valve guide is installed. 6-75