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AERONCA Engine Handbook Table of Contents Previous Section Next Section Index Home
PART V - COMPLETE OVERHAUL - Continued SECTION 4 - ASSEMBLING THE ENGINE After all parts have been inspected and properly reconditioned, the engine is ready for reassembly. The parts should all be carefully cleaned before assembly is started and care should be taken to avoid getting dirt into the engine as it is built up. The various bearings should be covered with clean engine oil as the parts are being put together. A lock washer must be used under all plain nuts unless so specified. Be sure to add the cotter pin or lock wire where required as soon as the parts are put together. It is advisable to use new cotter pins and new lock wire when reassembling the engine. For locking wire No. 18 soft brass wire may be used. Caution: Use a fibre mallet when driving parts together so as not to
injure them.
Replace the cam followers and camshaft assembly if it has been necessary to remove them. The camshaft bearings are a push fit in the crankcase. The cam followers are a tight fit in the crankcase and it is necessary to heat the crankcase to 250 to 300 F in order to install them. After the crankshaft assembly has been inspected and reassembled (see Section 3-N and Section 3-0, Part V - COMPLETE OVERHAUL) it is now ready to be installed in the engine. It is necessary to keep the connecting rods and crankpins in a horizontal position in order that they will slip through the opening in the rear of the crankcase. Be very careful to see that the connecting rods line up in the center of each cylinder as it is possible to get the right and left connecting rods interchanged and this may not be noticed until after the engine has been nearly assembled. The backplate assembly, including the oil relief valve, may now be assembled to the crankcase using a new backplate gasket. See that the oil return tube fits into the hole in the center section of the crankcase so that it will not be bent when the backplate is assembled. When installing a new gasket, oil the entire surface so that a good seal will be formed. The ball thrust bearing may now be slipped over the front end of the crankshaft and pressed into the crankcase. Make sure that the retaining ring, Part No. 310, is in place. The large locking washer, Part No. 291, should be placed against the thrust bearing and the nut, Part No. 717, tightened using too. No. T-14 (See Figure 5). Note: This nut is only to be used not he new type crankshafts, Nos. 687
and 721, as it has a different thread from the nut, Part No. 276,
used on the old type crankshaft, No. 423.
Important Note The thrust bearing nuts must be very tight in order that there will be no wear between the inner bearing race and the crankshaft as this would allow the crankshaft to have a considerable amount of end play which is not desirable. When tightening this nut with toll T-14, the crankshaft may be restrained from turning by placing a piece of hard wood or fiber through one of the connecting rod bushings allowing it to bear on the crankcase. Lock the thrust nut by bending over a section for the special lock washer. The front plate may now be assembled using a new gasket. It may be necessary to replace the felt oil retainer, if any oil has been leaking out through the crankshaft at the front end. Be sure to safety the four cap screws with wire. Slip the oil strainer in place and the three gears, being very careful that the camshaft and idler gears are properly assembled according to the marks on the teeth (See Figure 7). The pistons and cylinder assemblies will now have to be assembled in order that the valve timing may be checked before proceeding with the assembly of the gear cover and other parts at the rear of the engine. A. Assembling Pistons It will be necessary to heat each piston to approximately 212F in
order that the piston pin will slide into the piston. After the
pistons have been assembled to the connecting rods, it will be
necessary to snap the two piston pin retaining rings into place in
each piston.
To insert cold rings enlarge the ring, using a pair of pliers, as
shown below take hold of the one end with a pair of pliers and
wind up the ring forcing it into the groove. Smooth all sharp c
orners on the piston pin hole. The ring must be perfectly flat or
it will wear and enlarge the groove in the piston and eventually
scratch the cylinder wall.
Note: All new #418 snap rings (1937) have been made to larger
diameter so do not bend them open.
It is very important that these snap rings be installed correctly
or they may become loose and wear on both piston and cylinder.
B. Assembling Cylinders to Crankcase Follow the direction given in Part IV - TOP OVERHAUL, for the
assembly for the cylinders.
C. Valve Timing After the backplate is in place and the gear train completely
assembled the camshaft should be checked for timing before assembl-
ing the gear cover. (See Figure 7) The camshafts used in the
AERONCA engines are so designed that they are in a balanced
position when the pistons are on either T.D.C. or B.D.C. When
No. 1 piston is on T.D.C., No. 1 exhaust valve will be just
closing and No. 1 inlet valve just opening and the resultant
spring pressing on the valves will hold the camshaft in a balanced
position.
It is important that all valve tappets be set to the same clearance
when timing the engine.
1. Timing the E-107A Engine Set the valve tappet clearance of both inlet and exhaust
valves to .010". Due to the construction of this engine the
hot engine clearance will be practically the same as that of
the cold engine. The valve timing should be very close to the
following settings: (See Figures 7 and 8)
Intake opens 6 1/2 before T.D.C.
Exhaust closes 6 after T.D.C.
Exhaust opens 56 1/2 before B.D.C.
Intake Closes 56 1/2 after B.D.C.
The actual valve timing on the engine may vary slightly from
the above theoretical settings; however, the intake and exhaust
settings should balance, i.e., 5 - 5 , and 55 - 55 , etc.
If for any reason the camshaft does not give balanced settings
as outlined above, it will be necessary to reset the camshaft
gear on the 18 tooth spleen of the camshaft until this balance
is obtained.
Although the valve tappet clearance must be .010" while
checking the valve timing, it is advisable to make this clear-
ance .013" and use a .003" feeler gauge to determine the exact
point where the valves open and close. If a timing disc is not
available, use the magneto timing scale on the crankcase.
2. Timing the E-113, E-113A, E-113B & E-113C Engines These engines are timed in a manner very similar to that used
for the E-107A engine, except that the valve tapped clearance
measured between the rocker arm roller and the valve stem must
be set to .030". When timing the engine it is best to reset
this clearance to .033" and use a .003" feeler gauge, as
explained above for the E-107A. The valve timing should be
very close to the following setting. (See Figures 7 and 9)
Intake opens 5 before T.D.C.
Exhaust closes 5 after T.D.C.
Exhaust opens 55 before B.D.C.
Intake closes 55 after B.D.C.
The actual degrees on the engine may be slightly different
from the above but if balanced; i.e., 6 - 6 and 56 - 56,
etc., then the timing may be considered correct.
If for any reason the camshaft does not give even settings as
outlined above, it will be necessary to reset the camshaft
gear on the 18 tooth spleen of the camshaft until the setting
is correct.
Be sure to set the valve tappet clearance back to the normal
cold clearance of .005" on both intake and exhaust valves.
After the valve timing has been checked, tighten and safety
the camshaft nut which holds the camshaft gear in place. Check
the clearance between the backplate and rear face of gear.
This should be approximately .032".
D. Assembly of Gear Cover and Accessories Before clamping the gear cover tight to the backplate it is best
to set the magneto on the gear cover base and check the magneto
timing as outlined in Section 3-P-5, Part V, COMPLETE OVERHAUL.
(See Figures 5 and 7) It may be necessary to reset the idler gear
which drives the magneto through the magneto driver, in which
case be very careful when removing and replacing this gear so
that the relation between the camshaft and crankshaft gears will
remain the same. The pistons should be at approximately T.D.C.
when this is done as, in this position, the camshaft will be in
a balanced position and will not tend to rotate.
Place the gear cover gasket on the backplate and make sure that
the oil strainer and the oil pump driver gear are in place. Oil
all pats generously and attach the gear cover being careful to
see that the collar, spring, and locking plate on the oil inlet
spindle are in place.
After the gear cover has been attached, place the magneto driver
in its correct position (see Figure 7), bolt the magneto in place
and safety with wire. The tachometer shaft and bushings may now
be inserted in the gear cover. It is very important that this be
done in the following manner:
Screw the bushings in until it hits the end of the camshaft,
then back it out one full turn and tighten the locking nut
in this position.
The oil pump may now be attached. Make sure that the four cap
screws are safetied with wire. Small copper washer should be
placed under the three units which hold the oil pump in place in
the gear cover so as to prevent any oil leakage.
The intake manifold may now be assembled to the crankcase and
cylinders using new gaskets and hose connections, if needed.
When assembling the breather body to the crankcase be sure that
the cone (Part No. 407) and flapper valve (Part No. 417) are
correctly installed as shown in Figure 5. The flapper disc should
be placed so that it is to the outside of the crankcase.
The external oil line may now be connected to the oil pump, oil
relief valve and crankshaft inlet fitting. The breather oil drain
line may now be installed. This will include the Cuno oil filter
lines on those engines having filters. See Figure 12 at rear of
book.
To install the oil level gauge, insert the rod through the hole
at the top of the crankcase and snap on the float in the oil
reservoir at the bottom of the crankcase. (See Figure 3)
E. Fitting the Propeller Hub to the Crankshaft The following procedure should be used to "relap" the propeller
hub to the crankshaft:
Remove the propeller hub assembly, using Propeller Hub Puller,
Tool No. T-11, and examine the hub and crankshaft for any signs
of wear. If a red dust is present, it indicates that the two
tapered parts are not fitting together properly and should be
"relapped.." Be sure the puller is screwed on to the hub as far
as possible to prevent damage to the threads.
After cleaning the parts with gasoline, check the taper fit by
either drawing a number of pencil lines axially on the taper
shank of the crankshaft or by using some Prussian Bluing. Remount
the propeller oscillating it several times and remove.
Caution - Apply a small amount of oil to the taper shank before
checking as it is possible to gall the surfaces, if
they are dry.
To "relap," apply a slight amount of fine grinding and lapping
compound such as No. 2A Clover Brand or equivalent, to both the
front and rear bearing surfaces. Lap the surfaces together by
periodically oscillating the propeller and relieving the load
so as to obtain a good fit.
Caution - Do not under any circumstances rotate the propeller in
one continuous direction and do no "lap" any longer than
is necessary as the hub moves back along the taper shank
quite rapidly as metal is removed.
After "lapping," check the fit, using pencil lines or Prussian
Bluing, as explained above.
When both bearing surfaces show a good fit, apply a very small
amount of lapping compound to the small front bearing surface on
the taper shank and "lap" a slight amount more, using only oil
on the larger rear bearing surface.
Note: This operation is absolutely necessary in order to insure
a tight fit on the rear surface. Due to the difference in
the diameters of the front and rear bearing surfaces it is
necessary to lap the smaller surface an additional amount
so that the hub will fit tightest on the rear surface.
Clean both surfaces thoroughly, slip on the propeller hub assembly
and washer, tighten the nut and safety with a cotter pin.
Note: If the propeller hub has been lapped a number of times, it
may be necessary to countersink the small steel washer, as
shown below, in order that the propeller hub will be held
under a tension load from the nut.
Check the clearance between the head of the propeller bolts and
head of the bolts holding the front cover on engine. This clear-
ance should be at least 3/32". When mounting the propeller and
hub, it is very important to draw up on the propeller hub nut
very tight, using a socket wrench with an 18" arm, if available.
It is also important that the six bolts holding the wood propeller
to the hub be tight. It may be necessary to pull up on some of
those bolts more than on the others in order to properly track the
propeller; however, they should all be sufficiently tight to
prevent any movement between the propeller and hub.
The hub should be removed, checked and relapped every 100 hours of
flying.
It is usually advisable to install a new propeller hub on a new
crankshaft, if the old hub is galled.
SECTION 5 - "RUNNING IN" ENGINE Follow procedure given in Section 7, Part IV, TOP OVERHAUL.
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