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PART 9-1-GENERAL IGNITION SYSTEM SERVICE
9-11
~--------------------~30
KV
+-----------------------+25
+-----------------------+20
~------------------~~+15
'-~-+--+-~--+--+--~LI-NE_l~;
.....
,10
11997-A
FIG.
22-30
KV
Pattern
until that pattern fills the screen in
the same manner as in the secondary
test (Fig. 20).
The following list of symptoms
will refer to Fig. 20.
If the points open line (A) is
higher than the rest and the plug
firing line (B) is sloped downward
at an unusually large slope, there is
excessive resistance in the high ten-
sion wire to that cylinder or in the
distributor cap.
If the points open line (A) is low
and the firing line
(B)
is long and
nearly straight, the spark plug is
shorted out.
If the points open line (A) is low
and the firing line
(B)
is long and
wide, the spark plug gap is out of
adjustment.
If there are no oscillations at
points C or D, the coil primary
windings are partially shorted.
If the points open line (A) and
the oscillations at point D are both
displaced to the right on all cylin-
ders, check the breaker points.
I~
all of the points open lines (A)
are at varied heights, check the idle
adjustment of the carburetor (always
adjust the idle mixture on the rich
side).
30 KV PATTERN
Procedure
RE-235 TESTER. With the engine
running at 600 rpm, turn the test
selector switch to the 30 KV posi-
tion. Adjust the expand and parade
controls to produce the pattern
shown in Fig. 22.
RE-651 TESTER. With the rpm
selector at the 5000 position and the
engine operating at 600 rpm, depress
the 30 KV pushbutton. Adjust the
expand and parade controls to pro-
duce the pattern shown in Fig. 22.
RE-881 TESTER. With the rpm
selector at the 1600 position and the
engine operating at 600 rpm, depress
NO.1
FIG.
23-Sun 900 Tester Connections
the 30 KV pushbutton. Adjust the
expand and parade controls to pro-
duce the pattern shown in Fig. 22.
Results. A normal 30 KV pattern
is
shown in Fig. 22. The spark plug
line (A) for the No. 1 spark plug
is
on the extreme right hand side of
the screen. The remainder of the
"l'
o. 1 firing pattern is on the left
side of the screen. The remainder of
the patterns are shown from left to
right in their firing order.
Notice the average height of the
solid part of the points open line.
lncrease the speed of the engine and
notice the height of the dotted lines.
The difference is the required igni-
tion output under load. The maxi-
mum output should be between 13.5
wd 15 KV.
If
the maximum for one or more
uf the plugs is above 15 KV, check
the complete circuit ( s) of the
plug(sl for any trouble that would
cause this resistance.
If
the maxi-
mum docs not increase during the
increase in engine speed, check for
0
0 0
0
0
COIL WIRE REMOVED
a fouled or improperly gapped spark
plug or for very low compression.
Remove the high tension wire at
the distributor cap for any plug
except No. 1. Notice the change
between the average points open line
and the points open line of the
cylinder with the high tension wire
removed. This height difference is
the coil reserve. The coil reserve
should be at least 30% of the maxi-
mum output. If it is less than 30%,
replace the coil.
Remove and do not ground one
spark plug wire at the spark plug.
If
a plug firing line shows up on the
scope for that cylinder, check the
plug wire and distributor cap for
bad insulation.
IGNITION SYSTEM TESTS-
SUN 900 TESTER
TEST CONNECTIONS
Most of the ignition system can
be tested by using the Sun 900 Scope
Motor Tester. Make the connections
as follows (Fig. 23).
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Troubleshooting
