Pontiac FIREBIRD 1972 Service Manual page 1142

8-22 1972 PONTIAC SERVICE MANUAL
EFSAUST
MANIFOLD
(REF.)
TRANSMISSION
Fig. 8-23 Exhaust System Clearance Requirements (X Series 6-Cyl.)
Resonators are not used.
Pipe and mumer hanger assemblies are a "rubber block"
type (Fig. 8-14). This provides a rigid hanger along with
a feature that continues to support the exhaust system in
the event a rubber insulator block is broken. The hanger
assembly is made up of a rubber insulator block placed in
a stamped metal bracket which bolts to the underbody.
The supports holding components of the exhaust system
in place have a strap (blade) formed on one end that slips
into a slot in the hanger's rubber insulator block with no
clamping of the support to hanger required. The installa-
tion of exhaust system supports is very important as im-
properly installed supports can cause annoying vibrations
which are difficult to diagnose. When inspecting or replac-
ing exhaust system components make sure there is at least
3/4" clearance from the floor pan to avoid possible over-
heating of the floor pan and possible damage to the pas-
senger compartment carpets.
Check complete exhaust system and nearby body areas
and trunk lid for broken, damaged, missing or misposi-
tioned parts, open seams, holes, loose connections or other
deterioration which could permit exhaust fumes to seep
into the trunk or passenger compartment. Dust or water
in the trunk may be an indication of a problem in one of
these areas. Any defects should be corrected immediately.
To help insure continued integrity, the exhaust system
pipe rearward of the mumer must be replaced whenever
a new muffler is installed.
V-8 ENGINE
Two exhaust systems are used with V-8 engines
-
single
and dual (Figs. 8-24, 8-25, 8-26 and 8-27). Exhaust mani-
fold to crossover pipe (single systems) or exhaust pipe
(dual systems) connections are of the ball type, thus elimi-
nating the need for gaskets.
The single exhaust system crossover pipe passes under the
engine oil pan from left bank to right bank and then
connects to an intermediate exhaust pipe. The intermedi-
ate exhaust pipe runs along the right side to a rear exhaust
pipe connected to a tri-flow mumer mounted transversely
between the rear axle and fuel tank. The mumer is welded
to the tail pipe located on the left side which is connected
to an extension passing under the rear valance panel. The
mumer to tail pipe connection is clamped instead of
welded when either the tail pipe or mumer are replaced.
The dual exhaust system consists of two exhaust pipes,
one mumer and two tail pipes. The exhaust pipes are
two-piece with a front and rear section clamped together
forward of the rear axle. The rear section of each exhaust
pipe clamps to a single tri-flow muffler mounted trans-
versely between the rear axle and fuel tank. The mumer
is welded to the tail pipes which are clamped to extensions
passing under the rear valance panel. The mumer to tail
pipe connection is clamped instead of welded when either
of the tail pipes or mumer is replaced. The dual exhaust
system is standard equipment on Formula and Trans Am
models. A dual exhaust system is only used on X Series
in conjunction with special performance suspension.