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10-64 IGNITION SYSTEM
ELECTRICAL SYSTEMS
(340)
4. Attach condenser connector lead, breaker
arm spring, lock, and terminal connector lead
to insulating block on contact support by means
of the screw and nut. The head of screw and
condenser lead terminal must be on inner side
of block toward contact points, and the breaker
arm spring, lock, connector lead terminal and
nut must be on the other side of block in the
order shown in figure 10-75. Leave screw just
loose enough so that the screw can be shifted
in the slotted insulating block.
5. C6mpress breaker arm spring and bring
the points together, then install contact sup-
port and breaker arm on a new breaker plate
and install support lock screw. NOTE: A new
breaker plat
e
maybe attached to a block of
wood to
make
a fixture which can be held in a
vise. See figure 10-77.
POI NT SURFACES MUST MEET SQU
ARELY
IN ALL PLANES
Figure 10-76-Contact Point Alignment
6. With points closed, inspect for square
contact between mating surfaces of the two
points. Carefully bend support, if necessary, to
make points meet squarely. See figure 10-76.
'CAUT ION : Do not bend the breaker arm as
this may damage the rubbing block and loosen
the pivot bushing in arm.
\ 9 TO 23 OZ
.
TO JUST
SEP
A RATE
POIN
TS
I
Figure 10-77-Checking Breaker Arm Spring Tension
7. Attach hook of spring scale to breaker
arm at side of contact point and check the
tension required to just separate the points,
with pull exerted at an angle of
90°
with the
point surface. See figure 10-77. Tension must
be 19 to 23 ounces.
8. Adjust breaker arm spring tension to
specified limits by shifting the attaching screw
in the slot in insulating block, then securely
tighten the screw and recheck tension. If slot
does not provide sufficient range for adjust-
ment, bend the breaker arm spring with pliers
applied at curved section, but use care to avoid
nicking or distorting the spring.
9. Carefully remove contact points from
the new breaker plate and install them on
breaker plate of distributor on engine. Attach
condenser to breaker plate and connect termi-
nal connector lead to terminal stud.
10. Put one drop of light engine oil on
breaker arm pivot. Work a small amount of
petroleum jelly into a piece of clean cloth, then
hold cloth against distributor cam while crank-
ing engine a few revolutions. CAUTION: An
excessive amount of lubricant on cam may
throw off when hot and get
between
contact
points, thereby insulating the points and caus-
ing ignition failure.
11. Adjust contact point opening to .0125"-
.0175", using the dial indicator
(par.
10-45).
12. Set ignition timing
(par.
10-47).
10-47 IGNITION TIMING
a. Timing Marks
An ignition timing mark is stamped on the
flywheel and an index mark is stamped on the
edge of the timing hole located in flywheel
housing above the cranking motor. These marks
may be seen when the timing hole cover is
removed.
.The timing mark stamped on flywheel is
%"
wide, knurled, and painted yellow. The
1
/
8"
width provides a tolerance of one degree when
setting the timing. On Series 40-50, the timing
mark is stamped "ADV
4°"
and gives a timing
setting
4°
to
5°
ahead of upper dead center.
See figure 10-78. On
Series
70, the timing mark
is stamped "ADV
6°"
and gives a timing set-
ting
6°
to
7°
ahead of upper dead center.
The upper dead center mark on flywheel,
stamped "U.D.C. 1-8", follows closely behind
the ignition timing mark as the flywheel ro-
tates. See figure 10-78. This mark must not be
used for ignition timing.
I
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