CONTACT POINTS
Some of the difficulties that can be encountered when trying to measure point gap with a
feeler gauge.
MISALIGNED CONTACT POINTS
WOULD GIVE FALSE READING
.020"
~~~~T
AC TUA L '
O
3
O
"i---~---'---1
POINT
OPENING
PITTED CONTACT POINTS
COIL POLARITY
UNEVENLY WORN CONTACT
POINTS WOlJLD GIVE FALSE
READING
CONTACT POINTS THAT ARE
PROPERLY ALIGNED WOULD
GIVE TRUE GAP SETTING
In a negative grounded system, the negative or primary terminal marked with a (-) should be
connected to the breaker terminal. Coil polarity refers to the direction of high tension current
flow and should always be negative at the spark plug. Reversed coil polarity is almost al\vays
traced to reversed leads at the coil. A simple way to check coil polarity is to remove spark
plug wire at the plug and hold it about 1/
4
of an inch away from the spark plug \Vhile the engine
is idling. Insert the point of a wood lead pencil between the wire end and spark plug, Figure
F-16 and F-17.
If
the spark flares or feathers and has a slight orange color on the plug side of the pencil,
coil polarity is correct.
If
this occurs on the wire side of the pencil,coil polarity is reversed.
Reverse wires at the coil.
SPARK FLARES OR ~·
FEATHERS AND IS
LIGHT OR ANGE "-...,
IN COLOR ~;;,
-:::--1
f"\ __ _,,, '~- --'-~-
L114•J
SPARK FLARES OR~II :'
FEATHERS A ND I S '
LIGHT ORANGE ·,
IN COLOR
--~-t}-=1~--'~I __
L11~·c-J
RIGHT COIL POLARITY
WRONG COIL POLARITY
Figure 16
Figure 17
F-10
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