Cyl; Spark Plugs - Pontiac FIREBIRD 1972 Service Manual

ENGINE ELECTRICAL 6E-43
on point support and breaker plate just beneath points,
burned points (from oil or crankcase vapor between
points) are very probable. Points which have gone several
thousand miles will have a rough surface, but this does not
mean points are worn out. The roughness between points
matches so that a large contact area is maintained and
points will continue to provide satisfactory service. If dirt
or scale is present, points should be cleaned with a few
strokes of a clean, fine-cut, contactfile. Do not attempt to
remove all roughness or dress point surfaces down
smooth. Never use emery cloth or sandpaper to clean
points. If points are burned or badly pitted, they should
be replaced and cause of this condition found and cor-
rected. If this is not done, new points will also bum and
pit in a short time.
Adjust ignition timing as follows:
1. Adjust breaker point gap.
2. Connect power timing light.
3. Loosen distributor clamp screw and rotate distribu-
tor until power timing light shows that the proper
mark on the cover lines up with the mark on the
harmonic balancer. Tighten distributor clamp screw.
The timing specifications for various engines are
listed below:
6 Cyl.
-
All
..................................................
4" B.T.D.C.
307 V-8
-
Manual Transmission
................
4" B.T.D.C.
307 V-8
-
Automatic Transmission
............
8" B.T.D.C.
350, 400 and 455
-
Manual Trans.
............
8" B.T.D.C.
350, 400 and 455
-
Automatic Trans.
......
10" B.T.D.C.
SPARK PLUGS
PERIODIC SERVICE
Periodically (actual time depending on operating condi-
tions), plugs should be removed for cleaning, inspection
and regapping.
REMOVE
1. Remove spark plug wires.
2. Remove any foreign matter from around spark plugs
by blowing out with compressed air.
3. Using a 5/8" spark plug socket remove the spark
plugs.
INSPECT
Spark plug life is governed to a large extent by operating
conditions, and plug life varies accordingly. To insure
peak performance, spark plugs should be checked,
cleaned, regapped or replaced every 12 months or 12,000
miles.
WRONG RIGHT
Fig.
6E-58
Measuring Spark Plug Gap
CLEAN AND REGAP.
Clean spark plugs thoroughly using an abrasive-type
cleaner. All spark plugs must be of the same make and
number or heat range. Use a round feeler gauge to adjust
the spark plug gaps to .035" (Fig. 6E-58).
CAUTION: Before adjusting gap, file center
electrode flat. In adjusting spark plug gap,
never bend center electrode which extends
through porcelain center. Always make adjust-
ments by bending ground (side) electrode.
INSTALL
1. Inspect spark plug hole threads and clean before in-
stalling plugs. Corrosion deposits can be removed
with a 14 mm. x 1.25 SAE spark plug tap (available
through local jobbers) or by using a small, soft wire
brush in an electric drill. If a tap is used, coat it with
plenty of grease to catch any chips.
CAUTION: Use extreme care when using tap to
prevent cross threading. Also, crank engine
several times to blow out any material dis-
lodged during cleaning operation.
2. Install spark plugs in engine, and tighten to 15 lb. ft.
UNIT DISTRIBUTOR
The main features of the Unit Ignition System are shown
in Figures 6E-60 and 6E-61. A basic wiring diagram is
shown in Figure 6E-62.
A magnetic pickup assembly located over the shaft con-
tains a permanent magnet, a pole piece with internal teeth,
and a pickup coil. When the teeth of the timer core rotat-
ing inside the pole piece line up with the teeth of the pole
piece, an induced voltage in the pickup coil signals the
all-electronic module to open the ignition coil primary
circuit. The primary current decreases and a high voltage
is induced in the ignition coil secondary winding, which
is directed through the rotor and high voltage leads to fire
the spark plugs.