Pontiac FIREBIRD 1972 Service Manual page 751

6D-8 1972 PONTIAC SERVICE MANUAL
2. Hot engine operation
-
Engine temperature above
230°F.
The combined Emission Control System (C.E.C.) operates
similarly to the T.C.S. system. Its purpose is to provide
vacuum advance approximately 20 seconds after the
transmission shifts into high gear (manual transmission)
or Drive (high gear automatic transmission). The only
other time where the vacuum controlled spark advance
will be available in all other modes of transmission operat-
ion is with the engine temperature below 82°F.
C.C.S. SYSTEM CHECK
To check the system for proper operation, simply set tim-
ing (see dwell and ignition timing specifications) with
vacuum hose disconnected as described.
Then, proceed as follows:
S.C.S (All) and C.E.C. (Automatic Transmission)
With distributor vacuum hose connected and engine tem-
perature between 95°F and 230°F (S.C.S. only), shift trans-
mission into Drive (rear wheels raised) and accelerate car,
observe timing mark on harmonic balancer. Timing
should advance when the car shifts into high gear (T.C.S.)
or approximately 20 seconds after the car shifts into high
gear (C.E.C.) or after the car speed exceeds 38 m.p.h.
(S.C.S.).
T.C.S. (Manual Transmission) and C.E.C. (Manual Transmis-
sion)
With distributor vacuum hose connected, engine tempera-
ture above 95°F and below 230°F (T.C.S. Only), and clutch
pedal depressed, shift transmission into high gear, and
observe timing mark on harmonic balancer. Timing
should advance, as the Transmission is shifted into high
gear (T.C.S.) or approximately 90 seconds after the trans-
mission is shifted into high gear (C.E.C.).
DIST. VACUUM
,
BATTERY
0 .
+
ENGINE
. ,
-
OVERHEAT LIGHT
-
MANIFOLD
VACUUM
T E M P ~ R A T U R E
SWITCH
TRANSMISSION
SWITCH (N.O.)
20
SECOND
TIME RELAY (N.C.)
The deceleration feature is used on L-6 onlv and is omitted on 307 V-8.
THROTTLE
LEVER
Fig. 6D-12 Controlled Spark System (CEC) -
Schematic and Vacuum Routing