PART IV - TOP OVERHAUL

    A top overhaul may be required after 80 to 100 hours of severe engine
operation. The use of a top cylinder lubricant in the gasoline will do
much toward keeping the valves and valve guides in good condition and so
decrease the frequency of top overhauls.

SECTION 1 - NEED FOR TOP OVERHAUL

    The usual indication that an engine needs adjustment, or possibly a top
overhaul, is the reduction in the engine speed on the ground at full 
throttle. It will be found that the engine speed will vary with the air 
temperature and humidity and also with the direction of the prevailing 
ground wind. A drop in speed of more than 100 RPM may be taken as an 
indication of the need of a top overhaul. The following inspection and 
adjustment should be made before "revving up" the engine to full throttle 
on the ground to determine whether a top overhaul is necessary.

A.  See that the spark is fully advanced on the magneto. With the automatic
    spark control it should be fully advanced when the throttle lever is all
    the way in. The same should be true when the manual spark control is all
    the way in. (It is best to set the manual control so that the magneto
    will be fully advanced before the spark lever is against its seat. 
    This will eliminate any possibility of the spark not being fully advanced
    when the manual spark control is in.)

B.  Check over all of the adjustments given under Part III - PERIODIC 
    INSPECTION - for the daily, ten-hour, twenty-hour and one hundred hour
    checks.

C.  The carburetor throttle lever should open the throttle valve all of the
    way when it is against its forward stop.

D.  The Carburetor choke valve must be fully open.

    After the above checking has been completed and adjustments made, if
necessary, start the engine and warm it up slowly (600 to 800 RPM) until the
temperature of the oil is at least 90 F or 32 C. "Rev" the engine up to full
throttle with the spark fully advanced and note the maximum RPM. If the 
engine still does not turn up to the required ground speed it is probably 
that a top overhaul is necessary. After the engine has cooled down, and with
the ignition switch off, try the compression in each cylinder. It will be 
necessary to turn the propeller over two complete revolutions in order to 
test the compression in each cylinder.

SECTION 2 - TOP OVERHAUL OF E-107A ENGINE

    A top overhaul can readily be accomplished while the engine is installed
in the airplane.

    First, place the airplane in a clean protected spot free from dust and
dirt and remove the exhaust pipe and engine cowling. Next, the engine should
 be thoroughly washed off with gasoline before attempting any disassembly 
work. Disconnect the ignition cables from the spark plugs and remove the 
spark plugs. Unscrew the top cap screws with which each intake pipe is 
attached to the cylinder port.

A.  Disassembly of Cylinders

    Remove the cylinder head by removing the nine bolts on each head. The 
    heads should be marked so that they will be replaced on the correct 
    cylinders when reassembling. Be very careful not to injure the aluminum
    head gasket which is between the head and the cylinder.

    Remove the four cylinder base nuts and slowly pull the entire cylinder 
    assembly from the crankcase, catching the piston as it emerges from the
    cylinder. Do not allow it to drop as it will hit the two cylinder base
    studs and be damaged. The piston may be allowed to rest on a clean rag
    against the crankcase or against two pieces of hose slipped over the
    cylinder base studs.

    Cover the crankcase openings with a clean piece of cloth to protect the
    interior against dust and dirt.

    Scrape all carbon from the head and cylinder while the valves are still
    in place.

    To remove a valve, place a small block of wood under the valve with the
    cylinder up-side-down and depress the valve spring until the split cone
    can be removed. A steel bar approximately 1/4" x 1 1/2" wide x 12" long
    with a 3/4" hole through its center is very useful for depressing the
    valve springs. Remove the retainers, springs and valves, keeping note
    of their correct location so that they will be replaced in the same
    position when reassembling.

    Clean all parts with gasoline and inspect the valves for cracks and wear.
    Examine the valve seats. If they are found to be glazed and smooth all
    around and do not leak when gasoline is poured into the valve ports, 
    they are satisfactory, providing the valve seats are not over 1/8" wide.

    However, if the valve seats in the cast iron cylinder are worn deep and
    have shoulders or are badly pitted, they should be reseated before being
    reground. Before reseating, the valve guides should be inspected and, if
    found worn, should be replaced so that the pilot bar used with the
    reseating cutter will be better guided and so produce a much smoother
    seat. For method of changing guides see instructions in Section 3-D,
    Part V - COMPLETE OVERHAUL.

B.  Valve Grinding

    If it is necessary to recut the valve seats, a set of 15 , 45 and 70
    re-seating cutters should be used. These cutters will have to be of such
    a size as to take a valve seat diameter of 1 15/16". The pilot bar will
    have to be of 3/8" diameter for both intake and exhaust guides. It is
    well to remember that the cutters should be used very sparingly as they
    can be made to remove a considerable amount of metal.  If too much
    pressure is used, they will cut unevenly and it may be necessary to
    remove more metal to get true seat. If this has to be done very often
    the entire cast iron cylinder will have to be replaced.

    Use the 15 cutter to bring the O.D. for the 45 seat to between 1 13/16"
    and 1 7/8". Next, use the 70 cutter to bring the actual width of the 45
    seat to approximately 1/8". The 45 cutter is then used to recut the valve
    seat and this should be done with considerable care. Use very little
    pressure on this cutter and bear evenly all around, removing just as
    little metal as is necessary to clean up the weat.

    The carbon should be cleaned from the valves, care being taken not to
    scratch the seats. It is also important not to use emery cloth on the
    valve stems unless absolutely necessary, since it removes the glaze
    resulting from continued operation of the engine. If the valves are
    burned or pitted, they should be regrounded to 45 angle.

    After reseating the valves and seats, they should be "lapped in" by
    using a fine grinding compound so that there will be no chance for the 
    valves leaking. A final check should be made with gasoline.

C.  Valve Springs

    The valve springs should be examined for cracks and tested for deflection
    under load. They should require a load of at least 66 lbs to deflect them
    to an overall length of 2.75". All springs which require a smaller load
    should be replaced. Rusty springs should also be replaced as they may
    break at any time.

D.  Cylinders

    The cylinders should be checked for taper and out of roundness by the
    use of an inside micrometer. Cylinders tapered or out of round more than
    .003 - .004" should be rebored, to plus .005" or plus .020", if necessary.
    The cylinder walls should be smooth and free from scratches. If there
    are any deep scratches that will not clean up when the cylinder is
    rebored to the maximum oversize of plus .020" the cylinder should be
    replaced.

E.  Reassembly of E-107A Cylinder

    Before assembling, be sure that all parts are absolutely clean and in
    good condition. As the parts are being put together, oil all bearings
    and other contact surfaces.

    Replace the valves, springs, retainers, and split cone and test the
    valves for tightness by filling each port with gasoline. If they show
    signs of leaking they must be reground.

    The aluminum alloy head should be "lapped" to the cast iron cylinder
    using a fine valve grinding compound. This is absolutely necessary in
    order to insure a tight fit. Examine the aluminum head gasket to see
    that it is in good condition. If it is badly nicked or scratched, it
    should be replaced.

    Clamp the head to the cylinder using the aluminum gasket and tighten
    all bolts evenly. It is important that the small brass washers be used
    under the cylinder head bolts. If the head leaks slightly after the
    engine has been warmed up, draw up on the bolts again while the engine
    is still hot.

F.  Assembly of E-107A Cylinders to Crankcase

    Before assembling the cylinders to the crankcase, the interior of the
    engine must be inspected and cleaned, as outlined in Sections 5 and 6,
    Part IV - TOP OVERHAUL.

    Before attaching the cylinders, be sure that all parts are absolutely 
    clean and in good condition. As the parts are being put together, oil 
    generously all bearing and other contact surfaces.

    Space the piston ring gaps 120 apart before compressing them in a ring
    clamp and insert in the cylinders.

    It is best to use a gasket compound on the crankcase pad so that there
    will be no oil leakage when the engine is running. Permatex No. 2 Gasket
    Compound has been found to work very well for this purpose. A rubber 
    band 1/8" wide placed over the skirt of the barrel will act as an oil 
    seal very satisfactorily.

    Draw up evenly on the four cylinder base nuts. Be sure to use lock 
    washers under each nut.

    Set the valve tappet screws to .010" clearance on both intake and 
    exhaust valves. The intake pipe may now be connected. New intake gaskets
    should be used.

    Clean all spark plugs and check the gaps to see that they are 0.18". 
    Care must be taken that there are no burrs on the threads of the spark 
    plugs. This can be noticed if the plug screws in rather hard. In this 
    event, the plug should be removed carefully and the burr filed off or 
    the threads may be damaged and eventually the head will leak through 
    the spark plug hole.

    It is not necessary to time the valves or the ignition after a top 
    overhaul.

    Before attempting to start the engine, the routine inspection referred 
    to in Part III - PERIODIC INSPECTION - should be conducted and the 
    instructions given in Section 7, Part IV - TOP OVERHAUL should be 
    followed for "running in" the engine.

SECTION 3 - TOP OVERHAUL OF E-113 ENGINE

    A top overhaul of the E-113 engine is accomplished in a manner similar to
    that outlined for the E-107A engine. First, the airplane is placed in a
    clean protected spot and the exhaust pipe and engine cowling removed. 
    Next, the engine should be thoroughly washed with gasoline before 
    attempting any disassembly work. Disconnect the ignition cables from the
    spark plugs and remove the plugs. Remove the two nuts which hold each in
    take pipe to the cylinder port. In order to remove the cylinders, it
    will be necessary to loosen the hose clamps at the lower end of the
    intake elbow so that the intake elbow may be swung rearward to clear the
    port studs.

A.  Disassembly of Cylinders

    Remove the four cylinder base nuts and slowly pull the entire cylinder
    assembly from the crankcase, catching the push rods and tubes as they
    become loose. Do not allow the piston to fall from the cylinder as it
    emerges or it will be badly nicked as it will hit the cylinder base
    studs. A clean rag should be placed between the piston and crankcase or
    pieces of hose slipped over the two studs.

    Cover the crankcase openings with a clean piece of cloth to protect the
    interior against dust and dirt.

    Under no circumstances should the nuts be removed at the joint between
    the cylinder and the cylinder head as this a permanent joint.

    It is not necessary to remove the rocker arms in order to grind the
    valves. They should be taken apart only when some part is damaged or 
    indicates wear. Under no circumstances should the rocker boxes be removed
    as they are permanently attached to the cylinder head.

    Check the valves to determine which are leaking by pouring gasoline into
    each valve port.

    To remove the valves, place the cylinder over a block of wood. A 
    2" x 4' will do, providing the corners are beveled and one end is 
    rounded to fit the cylinder head dome. Clamp this block in a vise in an
    upright position. Depress the valve springs using tool No. FA-31. Remove
    the split cone, valve springs and retainers, then take off the small 
    ring which is snapped into a groove in the valve stem. This ring acts as
    a safety device in case the valve breaks near the split cone and should
    always be removed or assembled from the side instead of being pulled
    over the end of the valve stem.  To avoid damaging the valve guide when 
    removing the valve, inspect the stem end for burrs. If any are found, 
    they must be removed before the valve stem is pulled through the guide.

B.  Valve Grinding.

    After the cylinder has been disassembled, scrape all carbon from the 
    cylinder head and valves, being careful not to mark or scratch the valve
    seats and stems.

    It may be necessary to recut the valve seats, if they are pitted or have
    a hard scale on them. This should be done in a manner similar to that 
    previously described of the E-107A engine. (See Section 2-B - Part IV
    TOP OVERHAUL.)

    To grind the valve, spread a small amount of grinding compound around 
    the seat of the valve. Insert the valve in the guide and grind, using 
    tool No. FA-29 or a clamp which fits the end of the valve stem and has 
    an extension handle so that the valve may be oscillated during the valve
    grinding operation. Repeat this operation until a good seat is obtained,
    then wash the valve and cylinder carefully with gasoline so that no
    trace of the grinding compound remains and test for tightness.

    It is desirable to have the cylinder assembly held in a horizontal
    position when grinding the valves. A simple and handily fixture for 
    holding the cylinder in this position can be made by cutting a 4-1/2"
    diameter hole in 6" x 12" steel plate, 3/16" - 1/4" thick, or a 4-1/2"
    diameter hole in an 8" x 12" piece of hardwood 1" thick.  The cylinder 
    should be attached to this plate or piece of wood with two 1/2" diameter
    bolts holding the cylinder flange tight against the mounting. The other
    end of the plate or mounting fixture should be clamped in a vise.

C.  Valve Springs

    Examine the valve springs for cracks and test each spring by noting the 
    weight or load required to deflect it to an overall length of 1.25".

    The large outer spring should require a load of at least 40 lbs and the
    small inner spring, a load of 25 lbs. All springs which require less load
    should be replaced. Rusty springs should also be replaced as they are
    likely to break at any time.

D.  Cylinders

    The cylinders should be checked for taper and out of roundness by the
    use of an inside micrometer. Cylinders tapered or out of round more than
    .003" to .004" should be rebored to plus .005 or some multiple of .005
    as plus .010, plus .015 plus .020 or plus .025, if necessary. The
    cylinder walls should be smooth. If there are any deep scratches, it is
    best to replace the cylinder as it is usually impossible to remove them
    by grinding and it is not advisable to regrind to more than plus .025"
    oversize as the wall will be too thin for safety.

E.  Reassembly of E-113 Cylinders

    Before assembling, be sure that all parts are absolutely clean and in
    good condition. As the parts are being put together, oil generously all
    bearings and other contact surfaces.

    Replace the valves, being careful not to interchange those of the other
    cylinder and place the colander over the wood block, used for disassembling.
    Snap the safety rings into their grooves and assemble the valve springs
    and retainers. Depress the valve springs using tool No. FA-31 and insert
    the two halves of the split cone retainer.

    After the valves have been assembled, they should again be tested with
    gasoline for tightness and, if they still leak, the valve grinding should
    be repeated until they are tight.

    Note: If the rocker arms have been removed, they should be thoroughly 
          cleaned and inspected. The ball bearings must be assembled in the
          rocker arm with the shielded side toward the outside. Do not forget
          to place the small spacer between the two ball bearings. The
          bearings should be a push fit in the rocker arms. A ground steel
          washer is used between each ball bearing and the rocker box.

F.  Assembly of E-113 Cylinders to the Crankcase

    Before assembling the cylinders to the crankcase, the interior of the 
    engine must be cleaned and inspected as outlined in Section 5 and 
    Section 6, Part IV, "TOP OVERHAUL."

    Be sure that all parts are absolutely clean and in good condition. As 
    the parts are being put together, oil generously all bearing and other
    contact surfaces.

    Space the piston ring gaps 120 apart before compressing them in a ring 
    clamp and insert in the cylinders.

    It is best to use a gasket compound on the crankcase pad so that there 
    will be no oil leakage when the engine is running. Permatex No. 2 Gasket
    Paste has been found to work very well for this purpose. A 1/8" rubber
    band slipped over the skirt of the cylinder is a very satisfactory oil
    seal.

    Draw up evenly on the four cylinder base nuts and be sure to use a lock
    washer under each nut.

    It is desirable to assemble the push rods and tubes after the cylinder 
    has been bolted in place. When inserting the push rods, grease the ball
    ends and make sure that they fit in their respective sockets. The push
    rod tube should be installed first by compressing the retaining spring at
    the one end so that the tube will slide up into the rocker box. The
    other end can be inserted into the cam follower housing. The push rod is
    inserted by removing the valve tapped screw in the rocker arm and 
    inserting the entire push rod through this hole. The valve tappet screw
    is then replaced and the valve clearance set to .005" on both intake and
    exhaust valves. The intake pipes may now be connected using new gaskets
    and hose connections, if needed.

    Clean all spark plugs and check the gaps to see that they are .018". 
    Care should be taken that there are no burrs on the threads of the spark
    plugs. This can be noticed if the plug screws in rather hard. In this
    event the plug should be carefully removed and the burr filed off or
    the threads may be damaged and eventually the head will leak through
    the spark plug hole.

    It is not necessary to time the valves or the ignition after a top overhaul.

    Before attempting to start the engine the routine inspection referred to
    in Part III - PERIODIC INSPECTION - should be conducted and the 
    instructions given in Section 7, Part IV - TOP OVERHAUL - should be 
    followed for "running in" the engine.

SECTION 4 - TOP OVERHAUL OF E-113A ENGINE

    Follow the instructions given in Section 3, Part IV, TOP OVERHAUL,
for the E-113 engine with the following exceptions:

A.  Disassembly of Cylinder

    It is necessary to remove the rocker arms in order to grind the valves.
    All E-113A engines up to the earl part of 1934 have the construction
    shown in Figure 5C and all later engines have the new construction shown
    in Figure 10A. It is necessary to remove the Alemite fitting and holder
    in Figure 50 before the rocker arm shaft can be removed.

    Use tool No. T-12 to depress the valve springs when removing the valves.
    (This tool will also fit the valve tappet nuts.)

B.  Valve Grinding

    Use tool No. T-13 for grinding the valves. This tool is very similar to
    No. FA-29 used for the E-113 engine.

C.  Valve Springs

    The valve springs used on the E-113A cylinder are the same as used on 
    the E-113 cylinder for inspection and check.

D.  Cylinders

    See E-113 cylinders for inspection and check.

E.  Reassembly of E-113A Cylinders

    Before assembling be sure that all parts are absolutely clean and in 
    good condition. As the parts are being put together oil all bearing and
    other contact surfaces.

    Put the valves in place, being careful not to interchange those of the
    other cylinder. Place the cylinder over the wood block used for 
    disassembling. Snap the safety rings into their grooves and assemble 
    the valve springs and retainers. Depress the valve springs, using tool 
    No. T-12, and insert the two halves of the split cone retainers.

    After the valves have been assembled, they should be tested with 
    gasoline for tightness and, if they still leak, the valve grinding 
    should be repeated until they are tight.

    When assembling the rocker arms, reverse the procedure given for 
    disassembly. (NOTE: On some of the early E-113A engines the rocker
    arms must not be clamped tight because the bearing spacer was between
    the outer races of the rocker arm bearings.) This construction can be
    changed to the new type allowing the shaft nuts to be drawn up tight.
    (For further information write to the factory giving the engine serial
    number.) For all E-113A engines which have the new construction, i.e.,
    new spacers, aluminum bronze bushings in the outer head section which 
    are shrunk in place, etc., the shaft nuts may be drawn up tight. See
    Figures 5C and 10A. However, it is very important that the rocker arms
    oscillate freely. The valve springs and cylinders are the same as used
    on the E-113 engine, and the same sequence should be followed in regard
    to the Reassembly of the above parts. (See Section 3-E, Part IV,
    "TOP OVERHAUL.")

F.  Assembly of E-113A Cylinder to Crankcase

    Follow the same procedure as given for the E-113 engine, Section 3-F,
    Part IV, TOP OVERHAUL.

SECTION 4-A - TOP OVERHAUL OF E-113B AND E-113C ENGINES

    Follow the instructions given in Section 4, Part IV, TOP OVERHAUL for 
the E-113A engine, with the following exception:

A.  Disassembly of Ignition Wire Bracket

    It is necessary to remove the ignition wires and the nuts at the end of
    the ignition wire bracket tube. This will allow the two end sections of 
    the bracket to be removed with the cylinder. When assembling the bracket
    the four nuts should be drawn up snug after each cylinder has been bolted
    in place and then one of the inner nuts should be loosened one and 
    one-half turns and the outer nuts tightened this additional amount so
    as to put the tube in tension.

SECTION 5 - INSPECTION OF ENGINE DURING TOP OVERHAUL

A.  Pistons and Pins

    It is not necessary to remove the piston from the connecting rod in
    order to clean the carbon or replace the rings. The carbon in the head
    can be removed with some Crocus cloth dipped in kerosene. This will
    give a very high finish to the top of the piston which is desirable.
    It is well to remove the piston rings before cleaning the carbon so that
    the carbon may also be removed from the ring grooves. If the piston is
    badly scratched, it can be refinished with some Crocus cloth or a fine
    stone. However, if the scratches are very deep and numerous it is best 
    to replace the piston. For instructions on replacing pistons see 
    Section 3-E, Part V, COMPLETE OVERHAUL.

    The piston pins should fit tightly in the pistons at room temperature
    (70 F.) and should have a slight clearance in the connecting rod bushing.
    The piston pin retaining rings should be examined for tightness in each
    side of the piston. If they show signs of wear on the piston, it is best
    to remove them and replace with new ones as outlined in Section 4-A, 
    Part V, COMPLETE OVERHAUL.

B.  Piston Rings

    The piston rings should bear around their entire circumference and
    preferably have no more than .012" end clearance when the ring is in
    the cylinder. Moreover, they should be entirely free in the ring grooves.
    If it is necessary to replace the rings in one cylinder, it is advisable
    to also change them in the other so that the compression will be the
    same in each cylinder. For further instructions on fitting new piston
    rings see Section 3-4, Part V - COMPLETE OVERHAUL.

C.  Connecting Rod Assembly (Roller Bearing Type Only)

    The connecting rods should be checked for both side play and radial end
    play. If there is more than 1/32" to 3/64" side play in the connecting
    rod out at the piston pin, it is advisable to refit the connecting rod
    bearing, especially if the engine has had over 200 hours of service since
    the last complete overhaul.

    There should be no perceptible radial play in the connecting rod bearing
    as the maximum running clearance is only .0010". If the radial clearance
    exceeds this amount, it indicates that the rollers in the connecting rod
    bearings have worn considerably and should be replaced immediately. See
    Section 3-N and 3-0, Part V - COMPLETE OVERHAUL.

D.  Camshaft and Cam Followers

    The camshaft should be examined for wear on the cam surfaces. It should
    be revolved by turning the engine over slowly in order that the entire
    cam surface may be inspected.

   The cam followers should also be examined. The followers should be free
   in their guides and the rollers should not have any chipped or flat spots.
   If it is necessary to renew any of these parts, see Section 3-A and
   Section 3-C, Part V, COMPLETE OVERHAUL.

SECTION 6 - CLEANING INTERIOR OF ENGINE DURING TOP OVERHAUL

    It is important that the interior of the engine be cleaned out 
occasionally to remove all grit and sludge that has accumulated. If this 
foreign matter is not removed, it will continue to act like an abrasive
compound on the vital parts of the engine and will accelerate their wear. 
This cleaning can best be accomplished with the least amount of work by 
cleaning out as much of the interior of the engine as is possible whenever 
the cylinders are removed for a top overhaul.

    The oil should be drained from the engine and oil filter, and the sump 
cover removed. The oil pump assembly should then be removed after the oil 
lines to it have been disconnected. The interior of the engine can then be
cleaned with gasoline, using a brush or compressed air, and the sludge and 
grit will drain out at the rear side of the oil pump mounting. The oil 
reservoir in the bottom of the crankcase and also the oil screen at the 
inlet to the pressure pump, should be cleaned out.

    The oil pump should be washed out before being replaced and all of the 
moving parts in the engine should be well oiled before the cylinders are 
assembled to the engine so that they will not be dry when the engine is 
started.

SECTION 7 - "RUNNING IN" ENGINE

    It is desirable to operator an engine, which has just been given a top
overhaul, two to three hours at a slow idling speed of approximately 600 to
800 RPM. This is very important and should be done before attempting to run
the engine at full throttle or fly the plane. This "running in" should be 
done before replacing the engine cowling. Afterwards a check should be made 
for oil leaks and loose connections, fittings, etc.

    If a new set of rings or other new parts have been installed, it is 
desirable to run the engine at least four or five hours at idling speed, 
the last few hours of which may be run at 1000 RPM. It is preferable to 
operate it with the least possible amount of full throttle running for ten 
to fifteen hours thereafter in order that the new parts may be properly 
"run in."

     If the engine "revs" up to its customary ground speed and the oil 
pressure is around 10 lbs for the E-107A, 21 lbs for the E-113 and E-113A; 
13 lbs for the E-113B and E-113A with the Cuno Oil Filter; and 55 lbs for 
the E-113C, at full throttle, the engine can be considered in good shape 
and ready for further service. It is best to re-check the valve clearance 
after "running in" the engine. This must be done while the engine is cold 
or a false setting will be obtained.

     It is desirable to use a top cylinder lubricant when "running in" the 
engine. See Section 5 and 6, Part II - OPERATION.