the

Go%[Industries
INSTRUCT IONS
TYPE FM-E, X, Z
MAGNETOS
-
ENGINE ACCESSORIES OPERATION
BELOIT, WISCONSIN 53511
SERVICE INSTRUCTIONS
TYPE FM-E, FM-X, FM-XD, FM-XDE, FM-XE, FM-XF, FM-XFE,
FM-XFZ, FM-XO, FM-XOR, FM-XR, FM-XV, FM-XVE, FM-XY,
Fig. 1. Standard and Radio Shielded Magnetos
GENERAL DESCRIPTION
Fairbanks M o r s e S e r i e s X magnetos, Fig. 1, are-of the
rotating magnet dcsign. thd basic principle consisting of
inducing and continually reversing magnetic flux linen
- - - -~-.!-.~-z
~
rnru an lnoucrlon c~o u .~ l.n l .s is accompusneo
oy -.-.>.-~
rnp~ary
rotating the permanent magnetic rotor through a stationiary field whieh'is the baais of the magnetic circuit.
..~
~~~
........
~
~
-.~.~
.~
...
A one, two, or four-lobe c u n actuates a b r e a k e r mechaniam periodically during each revolution of the r o t a r .
Each t i m e the breaker points a r e separated by the magnetic rotor cam, an ignition spark i s produced. In the
one-cylipd~rmagnetos this oc5uy.s .oncep e r revolutionof
the rotor; In the two-cylinder magnetos the distributor
rotor f o r m s an axial exteneion of the magnetic rotor and
the breaker points a r e eeparated twice per revolutipn of
the rotor by a two-lobe cam. Similarly, in tho type
FM-XY four-pole magnktos, the distributor rotor forms
an axial extension of the magnetic rotor. Since the cam
of the rotor h a s four lobes, the b r e a k e r points separate
four t i m e s p e r rcvolutian producing four igpition sparks.
In the standard four-cylinder magnetos, a two-lobe cam
i s used which produces two i ~ n i t i o nsparks per revolution of the magnetic rotor, In all such c a s e s an ignition
spark i s furnished t o each hinh tension outlet, once f a r
ekery two reva1utior;fi of the m&netic rotor.
- . -
In the-FM-XR6 and FMZ6 six-cylinder magnetos, a t w o lobe cam i s used which produces two ignition sparks p e r
revolution of the magnetic rot0.r: A gear arrangement i s
used t o connect the magnetic rotor with the distributor
rotor which furnishes a s p a r k to each high tension outlet
.-=.- ~~ ~ . ~ - ~ - A L -.
.
...
.
........
!-
-.-~~
MAGNETO INSPECTION
The entire magneto ahould he inspected for worn p a r t s
every 1000 hours of operation.
End Cap and End Cap Removal
W h e n the usual inspection and s p a r k testa indicate poor
magneto p w f o r m a n c e , the end cap and end cap cover.
Fig. 2, if used, should be removed. Tag tho ignition
cables to insure their p r o p e r replacement in the endcap:
then remove each high-tension cable f r o m i t s socket. I n
the type FM-E magnetos, t h e e n d cap cover m u s t ,b,c!,,;::':
removed to. expose the high tension cable t e r m i n a l # bcr--j..::?;$. ,..
f a r e the lead S r e s can ba;embved.
~he;'r&oving
.::::'':'
end cap of the types EM-X4, FM:XR, FM-XOR;:.-?A!:~~!$;I$~:;F$
FM-XV magnetos, thc end cap cover mysf be..+SFb'$$&y:j;{T,
and the distributor r o t o r taken off t h e . - e n d ; < 1 t > g x ~ ~ ~ 3 ~ $ ~ ~ ~
shaft before the end cap can b e removed.
', ,~??;.
-
the::..
.....-... L'r..r,:>:;.;...?:'..J
~,~.~:~
....
. .,.,..,.
; . , A . , . .,.;;.;i.<r;:~;;;:
::;;,'
. . . . . . . . . . . . . . . . .., ,,,%, ,~
.c'
FILE SECTIONS-TYPE
FM-E, FM-X, FM-Z
. . . . . ...
. . <2,'.,
~ s t r u c . ~. . .i3..:r.o?. .,~3,. '::
~. ' ~ ~
Supersedes 3133 dated ~ u l ~ ; ' l $ i ~ '. I:,.: <;
March. 1973
--Pegc 2
10 .truct:on
Service Instructions
.'$-I
a r m spring. Thcn slide off the fulcrum pin snap ring
and lift the breaker a r m df the fulcrum pin. Take out
the two contact support locking screws, lockwashers,
and plate washers, and lift the support bracket f r o m the
bearing support.
Inspect the breaker points fur pitting o r pyramiding. A
small tungsten file or fine stone should be used to resurface the points. If the points are badly worn a r pitted
they should he replaced. When the breaker points have
been resurfaced or replaced he s u r e to adjust them to
their propar claarnnce of 0.015 f .OOZ in. a t Ngb polnt of
f
i
~
~ the following
~
~ manner
i :
cam. '
Loosen the two contact support locking screws. Insert
a aerewdrivor i n the horizontal slot at the bottom of t h e
contad support and move it by pivoting the tool between
the two small bosses on the bearing support until the
breaker points are adjusted t o the correct clearance.
Lack the assembly in place by tightening the locking
screws: then take a final measurement of the breaker
Oil
point gap after thc locking acrcws a r e tightened.
film should,be removed from t h e breaker points by using
a brush and a small quantity of petroleum solvent.
Fig. 2.
End Cap and High Tension Cdble Tarminala
Carbon Brush and Spring
Magnetos for engines with two o r m o r e cylinders have a
carbon brush and spring assembly in the center of the
end cap cover, Fig. 3. Multi-cylinder radio-shielded
magnetos have a distributor block in the end cap which
contains a carbon brush,and spring. Examine the brush
and replace it if worn o r damaged. The brush should
move freely in i t s holder and should be under slight
spring pressure. The high tension lead and suppressor
assembly can he unscrewed from the distributor block
for inspcction. cleaning or replacement.
Bearing Support with and without
Point Set, Condenser and Cam Wick
Fig. 4.
Breaker Arm, Support Bracket and Points
Condenser
Breaker paints ahould be checked and adjusted every 500
hours of operation.
Remove the standard condenqer from the magneto byun
screwing the condenser mounting screw. Fig. 5.
To
remove the feed-tbru condensers on thc FM-E6, FM-XE.
FM-XFE, FM-XVE, FM-XYE and FM-XZE m u l t i p l e
cylinder radio-shielded magnetos, take out the two candenasr mounting screws.
T o remove the breaker point aasembly, Fig. 4. take out
the breaker a r m terminal screw which releases the r o i l
lead wire. condenser lead, ground contact, and breaker
-
Clean the condenser and lead wire with a dry cloth: do
not damage t h e lead wire. Then inspect lead wire for
damage. Tent the .condenser for open circuit on a reliable condenser tester or substitute an identical new condenser i n ita place. The capacity of the AX-M-R-2433
condenser is 0.17-0.23 mfd. The capacity of the S-X-Y
Standard
...
Radio Shielded with Distributor Block
Fig. 3.
Magnetos with Brush and Spring
Feed-thru Condenser
n
P a ~ e
I
Instruction M3.1
servikc Inntructions
nuuun
PINION GEAR
I
Condenser nut shown
Fig. 6.
Two Typos of Bearing Supports, CW Rotation
-2433 Condenser i s 0.28-0.36 mfd. The capacity of the
L-V-2433 condenser i s 0.37-0.43 mfd. The canaeitv of
feed-thru condensers is as follows: HX2433 0.28-0.. 36
mfd. JX2433 0.17-0.23 mfd, KX2433 0.28-0. 36 mfd ahd
MX2433 0.28-0.35mfd.
Teet the condenacr a t 440v d r
for breakdown voltage.
-
.
Bearing Support A s s m b l x
Before removing the bearing support assembly, Fig. 6,
be s u r e the breaker a r m terminal screw has been rcmoved. On types FM-X4. FM-XE4. FM-XF, FM-XFE.
and FM-XZE, the magnstlc rotor gear must be removed
bofore the hearing support assembly can be taken out
of thc housing. Remove the magnetic rotor g e a r snap
ring and draw off the g s a r using the pinion gear puller
OMT76. Tho magnetic rotor gear pin can then be taken
out. On later model magnetos the new style magnetic
rotor gear (15952 can be easily removed after taking off
the rotor gear snap ring. Then take the bearing support
out of the magneto housing.
Coil
Fig. 6a. Use of
OMT76 Magnetic Rotor Gear Puller
- All FM-X
Magnetos
The removal of the coil in a l l magnetos will be e a s i e r if
the magnetic rotor i s turned to place the magnets in a
vertical position o r until t h e flux lock i s broken.
The coil in magnetos which have no reduction gear. Fig.
7, between the magnetic r o t o r and the distributor rotor.
can be easily removed f o r testing. Take out the breaker
a r m terminal screw, remove the coil lead w i r e and the
condenser. Loosen the coil bridge seteerews located on
top of the housing at each side, then slide the coil out of
the housing.
The coil in a maghato whlch h a s the distributor rotor
geared t o tbs magnetic r o t o r can be removed only after
the bearing support assembly has been taken out of tho
housing. Refer to paragraph Bearing Support Assembly.
On types FM-E, FM-XR and FM-XOR magnetoa, if the
bearing support i s hard to get out, remove t h e impulse
coupling on flange nlaunting magnetos, and Liftout the.oil
slinger baffle disc, replace the impulse coupling nut on
tho rotor shaft, and strike the shaft a aharp blow. This
will loosen the bearing support so it can be lifted out of
the housing. The outer race of the rotor cam end bearing will remain in the bearing support.
CCW Rotation
Clean the coil lead wire with Idry cloth; do not damage
the Lead wire. lnspoct t h o coil visually f o r cracks o r
exposed windings which would be cause for discarding
the Coil. Test the coil on a reliable t e s t e r .
Impulae Coupling
Although much s e r v i c e work can bc performed on the
magnetowithout taking the impulse coupling off t h e rotor
shaft, the removal of the magnetic rotor will necessitate
complete removal of the coupling. We recommend that
the coupling b e removed for cleaning and lubrication whenever m a j o r service work i s done on
the magneto.
An impulee coupling ia a mechanical device installed on the magnetic rotor shaft between the
magneto and engine drive. Ita prime purpose
i s t o intensify the ignition apark at low rotative
speed, and to automatically r e t a r d the ignition
spark during the engine atarting to eliminate
backfire.
C W Rotation
Fig. 7.
Bearing Support with and without Distributor G e a r
T h s impulae coupling assembly, Ftg. 8, consiota of a shell, flat o r coiled d r i v s spring and
coupling hub asacmbly with o r without pawl
springs, which i a keyed to tha magnetic r o t a r
shalt. The d r i v e spring has olio end engaged in
thc longer slat in i h c coupling hub while the
other end has a Loop formed which fits into the
coupling shell. T h e coupling shell is.fitted into
the drive member on the enginc d r i v e shaft.
Page 4
I n ~ t r u d i o n.d3-1
- --
Service Instruction
~ i g .8. Coupling Components:
H U ~ ,Drive Spring, and Shell
Fig. 8a.
When the engine i s operating at slow speed, the pawl in
the coupling hub engages the stop pin i n the magneto
housing, which prevents further movement of the magnetic rotor. As the engine continues to operate the shell
winds up the drive spring. At the point in t h e engine
cycle when the fuel mixture should be ignited, the pawl
ie released by movement of the coupling shell, and
snaps the magnetic rotar forward a t high speed through
its firing cycle. As the engine speed increases, centrifugal farce withdraw8 the pawls to a position where they
no longer engage the stop pin.
In applications where the magneto opqrates in other than
a horizontal position, t h e force of gravity cannot a d
upon the coupling pawls during the starting period. T o
cause the necessary s n g a g e m a a t a"tion, small e r e
springs a r e attached to each coupling pawl.
To remove the complete impulse coupling, take out the
impulse coupling nut lockwire o r turn down the lugs of
the impulse coupling nut lockwaeher; remove the i m pulse coupling nut and lockwasher. In the base mounted
magnetos, remove the impulse outer shell screws, lift
out the outer shell cupped washer and the outer shell
felt washer.
Remove the complete impulse coupling from t h e mag:
net0 by using the OMT8 puller. If the tension appned
by the puller does not loosen the coupling, tap the pull e r screw with a hammer, which will j a r the coupling
loose f r o m the rotor shaft. When the coupling is removed, lift out the coupling outer shell flat washer used
on base mounting magnetos. The coupling should he
disassembled only by an experienced service station.
In the event the shell comea loose from the hub when the
coupling nut i s taken off, care must be exercised in r e r. (i.>,..* +.,
assembly.
.
Coupling
butor rotor gear. remove the distributor shaft snap ring
and slide the shaft and gear f r o m the hearing support,
Fig. 9.
Ball bearings a r e used in the FM-E, FM-XR, and FMXOR magnetos, T o remove the d i a t.r i b u t o r b e a r h g
from these magnetos, take out the distributor ahaft snap
ring. Place a piece of aoft lead on 'the bench, turn t h e
bearing aupport over so t h e distributor shaft points
downward, grip the bottom of the bearing support with
both hands. and strike the end of the distributor shaft
on the lead a fear t i m c s t o j a r the shaft loose f r o m t h e
bearing.
Distributor sleeve bearings may be pressed out of their
respective bearing supports by means of the hand screw
presa 370TD. and the distributor bearing tool TD2252A.
T o remove the distributor b a l l bearing, take off t h e distributor bearing snap ring and p r e s s the bearing out of
i t s support.
Magnetic Rotor Types FM-X, FM-XV
There a r e t h r e e types of magnetic rotors used in t h e
seiies X magnetos: a two-pole rotor G t h block magnets; a two-pole rotor with b a r magnets perpendicular
to the rotor axis; a four-pole rotor with a cylindrical
magnet, Fig. 10.
-
Place the coiled end of the coupling spring i n the elot i n
the shell in the correct rotation for the magneto: clockwise for CW rotation, covntcrclockwise ior CCW rotation viewed when the coupling shell i s turned up. Engage
the straight end of the spring in the longer slot i n t h e
coupling hub and turn the hub one full turn, then push
the assembly together and install i t onto the magneto.
Distributor Gear Assembly
There a r e three types of distributor hearings used in
FM-X magnetos. An oilitc slceve bearing o r a niedle
bearing may be used in typee FM-X4, FM-XE, FM-XFZ
FM-XYE and FM-XZE magnetos. T o r e m o v e the distri-
Fig. 9.
Uoarirlg Support with Distributor Gear
Assenibly and Distributor Rotor
service instructions
Fig. 10. Twc-pole Rotor with
Rlock Magnets.
.
Two-pole Rotor with Bar Magnets
Placed Perpendicular to Rotor Axis
With the impulse coupling and bearing support removed,
take out the oil slinger baffle disc, found only on flange
mounting magnetos with integral flange. Then remove
tho rotor drive end seal outer washer by striking i t with
a punch on thc shaft edKc.
- This dishes the washer and
permits easy removal. On m o r e recent models, lha
rotor drive end seal outer waeher is made with one edge
cut flat making i t oasy to insert tho point of a scre&driver and loosen tho washer. Discard the waaher after
it has been removed from the magneto.
Page 5
Instrurti6n ~ 3 - 1
.
Four-pole Rotor with
Cylindrical Magnet
Remagnstiri~gMagnetic Rotor
Due t o the sxccptIonal stability of the Alnico magnets
usod in Fairbanks Morsa magneto., i t is recommended
that the rotor be r s r m ~ n c t i z e donly when it h a s bean
definitely determined that the ignition s p a r k i s bclow the
required minimum value.
Thc remngnetizinK vroceas
invilvc. the use of mitablo oqutpmcnt i n d shoild b e undertaken in accordance with t h e foliowittg instructions.
Magnetisation
Lift out the rotor drivc end seal and t h e rotor d r i v e end
scai inner wisher. Thts washer' is a loons fit but may
be difficult to rcmove due to the adheaion of bearing
grease. Finally, remove the magneto rotor shaft snap
ring which i s found only on the types FM-X, FM-XD,
FM-XDE, FM-XE. FM-XF, FM-XFE and FM-XZE magnetos.
P r e s s the rotor out of the housing. P l a c e t h e asnembly in the adjustable proas d t h tho t a m end of t h e rotor
shaft carcfuily centored in tho lntge hole of t h e base
plate. Then place the brnss p r o t e c t i v c cap over the
threaded end of the rotor shaft and apply an o v m p r e s sure by slowly turning tho drive screw. As soon a s the
rotor i n pressed out of the drlvc end bearing it may be
rcmovod f r o m the magneto housing.
In magnetos that have the rotor drive end bearing r e taining waaher. this washer must be removed before tha
hearing can be pressed out of the housing.
The l e n e h of the magnetizing time depends oo tho type
and strength of the charger. It is recommended that the
rotors be given a minimum charge of 30soeonda, broken
into two periods, o r "shots." Arrangements should bo
made to place the rotor in tha magneto housing as soon
as it is taken from t h e magnetizer.
Two-pble Rotors
Determine the polarity of t h e rotor and t h e magnetizer,
Fig. 11. Place the magnetic pole of the rotor, which
attracts t h e N pole of a compass, in contact with the
magnetic pole of the chnrger whtch attracts €he S pole of
the compass. By holding the rotor in the vicinity of a
charger while i t is in operation, the attraction of unlike
polea i s casily discernible.
All rotors oreopt those for type IFM-XV magnetos a r c of
the two-pole design and ohould be placed in the charging
blocks a s described above. The large radii of the charging blocks should be used for rotora f r o m types FM-E,
FM-XR and FM-XOR m a g n e t o B, and the small radii
should be used for rotors f r o m type FM-X units.
Four-pole Rotors
Four-pole rotors, Fig. 12. used in type FM-XV magnctoe, m u s t bo remagnetized wlth special care. Thcsc
rotors have large cylindrical magnets with the axis of
the poles pnraltel to the shaft. The magnetising blocks
muet be placed on the charger with m a d m u m surface
contact. Insort the rotor i n tho drilled holes o i the magnetizing block with the keyway up.
Drive End Ball Bearing
Fig. 11. Magnetizing Standard Two-pole Rotor with Bar
Magnets. To magnetize standard two-pole rotor with
block magnets, u s e aamc setup hnt
reverse charging blocks.
Rclcaae the bearing snap ring with anap rlng pliers, and
place the magneto in the hand Screw p r e s s 370TD. Put
a braes protective cap over the center of tho bearing,
Fig. 13. As tho screw i s turned down, contcr the assembly in the press. Apply p r e s s u r e evenly t o thc inner
bearing r a c e until the Inner bsarxng r a c e and hall rr-
Page 6
Inetruct~orlM3-1
loasen the old lubricant., Then inspect t h c b e a r i h g carefully. Replace any bearings that a r d frozen o r havc
broken balls, needles, or excessive axial play. Repack
each bearing with FMCO11 magneto bearing grease.
Sleeve Bearings
Oilite bearings, Fig. 16, found in scrvicoahle condition
during magneto overhaul may be replaced after soaking
them in turbine oil. Howaver. since these bearings are
relatively inexpensive i t i s recommended that a new
sleeve bearing beuscdwhen the magnetois reassembled.
Fig. 15.
SS
Needle Bearing
Fig. 16.
Sleeve Bearing
All other p a r t s should b e cleaned with a small, stiff
brush moistened with a petroleum solvent. Inspect a l l
castings and machined parts for chips, cracks, stripped
or mutilated thread or other defectb.. Inspect a l l gears
for chips, cracks, broken teeth: all bearing aurfaces
and keyways and all springs f o r banding, cracking o r
loss of tension. Replace any defective parts.
REASSEMBLY OF MAGNETO
If during the overhaul of the magneto the housing has
been cleaned with any type solvcnt solution, be s u r e to
remove any t r a c e s of the solution with water and finally
remove any remaining water and foreign material with a
MAGNETO FRAM
Fig. 13. P r e s s i n g Ball Bearing Out of EIousing
taining ring a r e pressed out. The outer bearing race
will remain in the housing and may b e pressed out if desired. If the bearing i s of the non-separable type. the
outer race driver must be used with 370TD band p r e s s
to press the entire bearing out of t h e housing
i' '4-
L
a:., / " -
Ball and Needle Bearings
Clean the grease out of the ball bearing, Fig. 14, and
the needle bearings, Fig. 15, if used, by soaking them in
a petroleum solvent, turning the bearing cage slowly to
BALL BEARING R E
INNER RACE
Fig. 14. Separable and Non-soparable Ball B e a r b g s
Fig. 17. Pressing Rotor Drive End
Bearing into Housing
Two-pole Rotor with l'erpenrliculsr LIar M a g n e t s .
Four-pole Rotor witlr Cylindrical Magnet
Fig. 18. P r e s s i n g Sleeve Bearing into Bearing Support
P e t r o l e u m solvent. Then d r y t h e housing thoroughly bef o r reassembling t h e magneto.
Rcplscement of Drivc End Bearing
T > W C I FM-XI, Fh4-X2, FM-X4, FM-XE4
The d r i v e end ball bearing used in types FM-XI, FMXZ, FM-X4, and FM-XE4 magnetos, when cleaned, inspected, and repacked with F M C O l l magneto bearing
grease, m a y b e replaced i n t h e housing, Fig. 17. Cent e r the bearing by hand, i n the housing, and place the
P l a c e t h e bearing above
housing i n t h e s c r e w p r e s s .
the support block carefully centering i t with t h e bearing.
Then t u r n down the d r i v e s c r e w of the p r e s s , placing
the b r a s s cap between the drive screw and the aupport
block.
B e s u r e t h e a s s e m b l y i s perpendicular in t h e
p r e s s b e f o r e forcing t h e bearing into t h e housing. R e
place t h e magnetic r o t o r drive end bearing anap ring.
Replacement of Sleeve Bearings
P u s h t h e new sleeve hearing on t h e end of tool TD2252A
and place t h e bearing support plate and t o a l i n the 370TD
hand screw p r e s s i i n t h e s a m e position a e f o r removal,
Fig. 18. Apply a n even. gradual p r e s s u r e , pushing t h e
hearing into t h e bearing support until i t i s flush with the
b r e a k e r side of t h e plate. When both the-magnetic t o t o r
b e a r i n g l b c e t h e d i s t r i b u t i r bbaking'i'h types FM-XFZ,
FM-X4, and FM-XE4 magnetos have been replaced, t h e
bearing support i s r e a d y to be replaced i n t h e housing.
P r e s s the distributor ball bearing into its r e c e s s , types
FM-E, FM-XR. FM-XOR, using t h e 370TD p r e s s , and
replace t h e distributor bearing snap ring. T h e n p r e s s
the distributor shaft into place using the hand p r e s s . and
replace t h e distributor ahaft snap ring. T h e b e a ? i i g
support i s r e a d y to b c replaced i n t h e housing.
Reasscmbly of Magnetic Rotor
Typcs FM-XV, FM-XOR, F M - E
P l a c e a new magnctic r o t o r bearing oil s e a l in thc d r i v e
end recess of the rotar, and a new magnetic rotor s e a l
T w n - p o l e Ilotnr with Black M a g n e t s
Fig. 19. T h r e e T y p e s Magnetic Rotors
Assembled i n Housing
in t h e c a m end recess of t h e r o t a r for type FM-XVmagnetos, Fig. 19. Slide t h e bearing t h r u s t washer next to
t h e m a g n c t i c r o t o r g e a r o n r a t o r s IOT lypea YM-XR,
FM-XOR, and F M - E magnetos. Pl&cc t h o assembly
t h e hand s c r e w p r e s a a n d with t h e r o t o r accurately
aligned with t h e bearing race, preas t h e inner b e a r i n g
r a c e onto tho r o t o r using t h e inner r a c e d r i v e r OMT82
as a n auxiliary toal.
P r e s s the b e a r ~ n g race for t h e
d r i v e end bearing of t y p e s FM-XR, FM-XOR, and FM-E
magnetos onto the r o t a r until i t r e a c h e s t h e shoulder of
t h e lamination assembly. P r e s s the races f o r the other
b e a r i n g s onto t h e r o t o r as f a r a s the w a s h e r s and cork
s e a l s will p e w i t . P l a c e t h e ball r e t a i n e r on tho inner
hearing r a c e s and r e p l a c e the rotor and bearing into t h e
housing.
Replacement of Magnetic Rotor into Rousing
Typcs FM-Xi. FM-XZ. FM-X4
The magnetic r o t o r types FM-XI, FM-XZ, FM-XF2 and
FM-XE4 magnetos m u s t b e p r c s s e d into t h e housing,
Fig. 20, using t h e 37OTD'acrcw p r e s s . P l a c e housing
I" the p r e e s with t h e d r i v e end bcaring accuraloly cent e r e d o v e r the l a r g e hole i n b a s c plate. Than, with
b r a s s cap o v e r c a m end of t h e r o t o r , p r e a s the rotor
into t h e b e a r i n g until t h e shoulder of the lamination a e sembly touches the i n n e r race of drive end bearing. R e place thc r o t o r d r i v e end shaft snap ring i n i t s groove on
Service Instruction
w1U tlle marked tooth of the distrSbut6r gear. Fig, 22.
when reasaambling n clockwise magneto the gears must
rnealr ao that the tnothpaintetl red on the magnetic rotor
will mesh between the two teeth on t h e distributor gear
marked "C".
On a counterclockwise magneto the r e d
tooth on the magnetic rotor gear must mesh between tho
two teeth m the distributor g e a r marked "A".
Fig. 20. &placing Rotor Drive End Shaft Snap Ring
Fig. 22. Gear Markings
the rotor shaft; replace the rotor ahaft seal inner washer, rotor ehaft seal and rotor shaft s e d outer washer.
Rotation of Coupling Drive Springs
When replacing the magnetic rotor on the FM-0, FMXO, FM-XOR. FM-XY. FM-XV and .all magnetos with
three piece ball bearings, end end play tolerance of the
magnetic rotor between i t s bearings should be held below 0.007 inchea.
Coil Replacement
Before replacing bearing support, set the coil. FSg. 21,.
in the housing. Tighten the two coil bridge sstacrews
and seal them with a drop ar two of,gasket varnish.
The coupling drive spring can be used f o r either rotation
by simply turning i t over. Care must be taken to place
the spring correctly in the shell. since incorrect assembly will damage the inside anchor end. Fig. 23. ~ 1 1 ~ s t r n t c s tho o o r r s c t location of drive springs in s e r i e s U
coupling shslla. Catch t h e inner end of the drive spring
i n the longer slot of the ooupling hub and complete t h e
aaacmblybyrwinding the drive spring one full turn. P u s h
t h e assembly together and key the coupling onto t h e
rotor shaft. Replace the impulae coupling nut lockwasher, screw t h e impulse coupling nut into place, and
turn up the lugs on the impulse coupling nut lockwasher.
o r replace the coupling nut lockwire. if used.
SPRING ANCHOR IN SHELL
COUPLING DRIVE SPRIIM
/
CCW ROTATION
Fig. 21.
Cutaway of Molded Coil
.
Replrcemmt of Bearing Support Assembly and
lntcrnnl T i d n g Replace the distributor shaft and gear assembly i n the
bearing support of types FM-XFZ, FM-X4, and FM-XE4
magnetos and s e c u r e i t in placewith the distributor shaft
snap ring. Fasten the bearing support assembly i n the
housing. Replace the magnetic rotor gear pin and magnetic rotor gear. The former can be tapped into position by placing a hollow cylindrical tool, such a s the
OMT82, over the c a m end o f t h e rotorwitlithe gear p a r tially i n place, and striking the cylindrical tool a few
light taps. On later model magnetos the new type magnetic rotor can be easily assembled on the cam end of
the magnetic rotor without special tools. A snap ring
holds this gear onto the shaft. Care must bc exercised
in meshing tho marked teeth of the magnetic rotor gear
CW ROTATION
Fig. 23. Position of Drive Spring i n Coupling Shell
Aaaembly of Breaker Mechanism
Remount the condenser on tho hearing support. On t r p e
FM-XV magnetos t h e c a m wick and holder as#amI!ly ie
mounted on the wndbnsar m o d i n g screw, along with
tho condenser. On a l l other magoeton except those with
feed-thru condensers the cam wick and holder 'assembly
i s supported hy the No, 8 contact aupport locking aerew.
Remount the broakcr arm aupport brnoket by means of
tho two support bracket Locking screws, l o c h a s h o r s ,
and flat waahors. Slidc t h € a r m onto tho fulcrum pin and
replacc the Iulcrum pin snap ring.
Place the lead wire terminal from the coil, the terxbinal from the condenser, the terminal from the ground
switch, and the end of the breaker a r m spring onto the
breaker a r m terminal screw, and faaten thie screw i n
-
.
page 9
Instruction M3-1
- .,
Service Instruclians
,
COUPLING SHELL
0 nu'
/
LOCKWASHER
Fig. 24.
Magnetic Rotor and Disassembled Impulee Coupling
the bottom of the aUDDort
- - bracket. Measure the breaker.
paint clearance and adjust the clearance i f necessary.
Refer to paragraph
under Breaker Arm, Support Brack.
.
et and Points,' far details on adjusting breaker paint
clearances.
marks onyour particular engine. Then rotate the crankshaft until the timing m a r k s coincide, indicating that the
No. 1 cylinder is i n advance-spark firing position. Be
s u r e that the piston is on i t s compression stroke.
Impulse Coupling T r i p Method
Sealing Magneto
Coat the contact surface of the end cap of t h e standard
magnetos with Fairbanks Morse FMCOZ Gasketvarnish.
P l a c e e new gasket i n t h e joint and fasten t h e end ca$ on
the housing with the end cap screws. Push a new distributor shaft seal into the distributorsshaft receas i n
the end cap of types FM-XI, FM-XFZ, FM-XR, FMXOR and FM-XV4B7 magnetos. Replace the dietributor
rotor on the end of the distributor shaft, pushing i t into
place a s far a s i t will go. Then replace the end cap
cover using a new gasket.
TIMING MAGNETO T O ENGINE
Accurate timing of the magneto t o the engine produces
an ignition spark in each cylinder a t the u a c t instant the
fael mixture should be ignited for best engine performance. This .indtaht, wliich i s determined by the engine
manufacturer, i s designated a a a given number of degrees of angular travel of the crankshaft before the
pietan reaches inner dead center on the compression
stroke. When starting the engine, it i s advisable to ret a r d the ignition spark until it occurs late enough in the
cycle to avoid backfiring. Impulse couplings when used
with magnetos automatically provide this spark retarding feature while the engine i s being started.
Magneto: Remount the end cap cover an the end cap.
Set the magneto for spark discharge to the No. 1 terminal. This may be accompl<shed by use of a stiff, short
length of w i r e placed in t h e No. 1 socwet a%d beht' to
within 1.18 in. of the magneto frame. Then turn the
magnetic rotor from .the impulse coupling end in ita
normal direction of rotation until a spark i s observed
beween the w i r e and the housing. Hold the coupling in
the position in which the t r i p occurred.
Engine: Remove the spark plug, o r otherwiee determine
top dead denter for the piston in the No. 1 cylinder.
Then turn the engine over until this position i s reached.
baing certain that the piston i s just at the end of i t s
compression stroke.
Coupling Magneto to Engine
Without disturbing the setting of either magneto o r engine a s determined by the methods above, couple the
engine in the following manner
Flange Mounting Magnetos: Engage the d r i v e lugs of the
impulse coupling with the driving slots of t h e engine
drive member. A slight movement of t h e engine flywheel may be necessary t o secure accuratm alignment.
Tighten capscrewe and nuts securely.
The importance of correctly timing the magneto to the
engine cannot be ovcrem~hasized, and the steps desciihed below ahould b s &llowed Larcfully. ~ i i h e the
r
advancd spark position method a r the impulse coupling
t r i p metbed may be used. Whichever mithod i s used.
the breaker painta must f i r s t b e accurately adjusted to
secure proper timing of the ignition spark.
Base Mountins Magnetos: If no change h a s been made
i n the position of the member, it i s n e c e s s a r y only to
engage the drive lugs of the impulee coupltog with the
drive slots of the float disc. Be aure that t h e shaft asaembly i s properly aligned before securing the base
mounting screws.
Advance Spark Position Method
Adjustable Drive Members
.
the magnevo f o r advance s p a r k position in
.>.."..,Y
~agnet:: ;set
the No. 1 cylinder. This i s done by turning the rotor
from the coupling end in the direction oppositeto normal
rotation until the distributor contact lines up exactly
with the timing boss. With certain exceptions the No. 1
outlet on four-cylinder magnetos i s the upper left of the
four terminals. On type FM-XOR six-cylinder magnetos
the Nq. 1 cylinder outlet i s usually diagonally upward,
30° to the left of vertical. When the magneto is timed
for advance spark in the No. 1 cylinder, i t should be
held exactly in the position until =&pled to the engine.
Engine: Engine builders usually indicate by m a r k s on the
flywheel and flywhcel housing, the position of t h e engine
for advance spark timing. Refer t o the engine manufact u r e r ' s instruction book for details concerning timing
Mast engines uslng base mounting magnetos a r e equipped with adjustable drive members, Fig. 25. Ordinarily
the position of the drive member i s not altered when r e ULSE COUPLING
L
M
Fig. 25.
Adjustable Drive Member
moving the magneto bukwhnn noceasary, the drive mllar
nut L can be loosened to permit relative movembnt of
the engine drive shnlt i n collar K The drive member
slots J can then h a turnad for alignmentwith the impulse
coupling luge, after which thc nut L should bc tiglrtoncd.
The locking lugs M of the washer should be turned up
around the nut to prevent it$ corning loose.
On the self-mountcd ground w i t c h , a wire is rue from
the p d m a r y terminal of ihc cail to a spring switet,
mounted on t h e magneto huunirlg an4 is no arranged thnt
when oparatnd the p n m n r y circuil i r grounded. On rho
mounted switch the same prillmry coil wlre i s extendcd
lo the control panel, usunlly through an mtermodiate
terminal mountad on the magneto.
Primary Ground Switches
When stopping the engine by grounding out the primary
circuit, thc switch must be kept closed until the engine
atops.
Englhea may be &topped by shutting off the fuel supply
or grounding out the nagnoto ignition circuit. Shutting
off ihe fuel supply has tho Qisadvantage of not stopping
the engine quickly, while grounding the ignition circuit
stops tho engine at once.
Battery ignition systems must be opened to stop the
engine while in magneto ignition systems the ignition
circuit must be grqunded to stop the engine.
Primaryground swtlihes must be located in the primary
circuit of either typo magneto, Fig. 26. The action i.
in8tnnbaneous and iuel is left in the fuel system for immediate starting.
~ h s r aare many typsa o r stylea of ground switches,
but in general they may he divided into two groups,
those located on the unit and those located away from
t h e unit.
Radio Shielded Magnotps
The high voltage spark discharge, which provides ignition for the engine, often causes interference in radio
reoention. Presuentlv it i e nacessarv or desirable to
+liminatf thls intcrfetf;ence, Fig, 27, 'lo principle, the
radio shielding of a magneto requires the r c p l a e m e n t
of the plastic cnd cup by an aU metal end Cap wlth an insulated plnstic distributor bloc% mounted inside. SpeCial
outlets are provided for t h e metal encased high tonston
cables, and the spark plugs a r e metal covered. All this
exterior metal housing ia intorconnected and grounded
to function a s a shield and absorb the interference causing waves. On certain magnetos for military applications the primary ground terminal is located on the end
of the feed-thru condenser o r on the end of the primary
circuit cannectar.
Fig. 26. Push-button and Lcver Type Type Ground Switchcs
N g . 27.
Complcte.Radio Shielded Magneto