TM 1-1500-204-23-1 NOTE Newly    installed    engines    shall    be given  a  depreservation  run  as  soon as   possible,   but   not   later   than   4 hours after preoiling has been accomplished  if  more  than  4  hours has  elapsed  since  preoiling  engine, complete   preoiling   procedure   shall again be accomplished. (1)   Prior to starting engine, remove one spark plug from  each  cylinder  below  the  horizontal  centerline  of engine.    Refer  to  TB  55-2925-200-25  for  proper  spark plugs to be utilized during depreservation run. NOTE On    seven-cylinder    engines    which would  necessitate  removal  of  spark plugs   from   four   cylinders,   thereby resulting in excessively rough operation, the one cylinder below the horizontal centerline on right side of engine     when     viewing     engine     at propeller  end  may  be  left  operative. This permits operation of four cylinders   rather   than   three,   which greatly stabilizes engine operation. (2)    Install  approved  depreservation  valve  in  each open plug hole. NOTE Install     length     of     hose     on     each depreservation   valve   to   vent   large quantities   of   oil   overboard.      This eliminates a fire hazard and accumulation  of  oil  around  cylinder or baffles. (3)    All  spark  plug  leads,  except  those  removed  to permit Installation of depreservation valves, will remain connected to spark plugs.  Install metal shipping caps to disconnected leads. NOTE The metal shipping caps ground out the ignition, thereby eliminating excessive    voltage    buildup    in    the magneto and possibility of flash-over at terminal end of ignition lead. (4)  Start engine and run at 800 to 1500 rpm for 30 seconds  to 1 minute.  Operation may be accomplished on    either    primer    or    carburetor,    or    both,    to    obtain smoothest possible operation. NOTE · Normally, smoothest engine operation   is   obtained   at   higher engine  speeds  and  a  higher  air velocity through Intake pipes will result   In   cases   where   extreme cold   temperatures   exist,   engine to be started should be preheated   prior   to   starting   and should  be  allowed  to  run  longer than the 1-minute period, provided   excessive   vibration   Is not encountered. · Corrosion-preventive  compound, if   present   in   Intake   pipes,   will have  adequate  time  to  be  heated and flow from Intake pipes through   external   drain   or   into combustion chamber and be expelled  into  exhaust  system  or through depreservation valve. (5)  Stop engine by closing throttle and discontinuing use   of   primer   or   by   moving   mixture   control   to   IDLE CUT-OFF position. (6)      Install    spark    plugs,    Ignition    leads,    engine cowling,    etc.,    and    proceed    to    start    engine    using prescribed starting procedures outlined in the applicable flight manual. NOTE Spark plugs used for depreservation runs  shall  be  replaced  with  new  or overhauled spark plugs before placing the engine in service. 7-47/(7-48 blank)