Pontiac FIREBIRD 1972 Service Manual page 1133

FUEL TANK AND EXHAUST SYSTEM
8-13
station wagon, a "kick-under" pipe from the muffler
passes under the axle tube to a resonator and then the tail
pipe crosses from right side to left side in front of the rear
frame crossmember. CAUTION: Use care not to crush the
"kick-under" pipe when using an axle engaging hoist.
A resonator is used on all exhaust systems except the 350.
It allows the use of mufflers with less back pressure and
provides for optimum tuning characteristics of the ex-
haust system.
The clamp joints at the exit end of all mufflers and inlet
of the resonators are indexed to the tail pipe or kick pipe
by a key (tab) welded on the pipe and a slot in the muffler
outlet pipe and resonator inlet pipe.
Conventional rubber strap type hangers are used with the
exception of the sedan and coupe muffler and tail pipe plus
rear of the station wagon and commercial chassis resona-
tor which are a "rubber block" type (Fig. 8-14). The block
type 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 frame. 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 installation of exhaust
system supports is very important as improperly installed
supports can cause annoying vibrations which are difficult
to diagnose. When inspecting or replacing exhaust system
components make sure there is at least 3/4" clearance
from the floor pan to avoid possible overheating of the
floor pan and possible damage to passenger 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(s) and resonator rearward of the muffler must be
replaced whenever a new muffler is installed.
A & G SERIES
6-CYLINDER ENGINE (A SERIES ONLY)
The 6-cylinder engine exhaust system (Figs. 8-15 and 8-
16) has a single outlet exhaust manifold. A seal is installed
between the manifold and exhaust pipe connection. There
is a steel extension sleeve that fits into the seal inside
diameter to provide support. The manifold is connected
by a one-piece exhaust pipe welded to a tri-flow muffler
clamped to the tailpipe. The exhaust pipe to muffler con-
Fig. 8-14 Installation of Rubber Block Exhaust System
Hanger (F Series Shown)
nection is clamped instead of welded when either the pipe
or muffler are replaced. The muffler and tail pipe are
indexed together by a key (tab) welded on the tail pipe and
a slot in the muffler inlet pipe.
Resonators are not used.
The exhaust system is supported by conventional rubber
strap type hangers and clamps attached to the frame and
they keep the exhaust system in proper alignment. The
installation of these supports is very important, as improp-
erly 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 muffler 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. 8-17, 8-18 and 8-19). Exhaust manifold to
crossover pipe (single systems) or exhaust pipe (dual sys-
tems) connections are of the ball type, thus eliminating the
need for gaskets.