Exhaust - Chevrolet 40 Series 1972 Service Manual

S e c . 6A
Page 12
G A SO LIN E ENGINES
ADAPTER
UNDERPAN
EXTENSION CO VER
Figure 1 — Flywheel H o u sin g and Adaptor Plate
(350 and 366 V8 Engine)
P roper functioning of the carburetor is p ar­
ticu la rly esse n tia l to control of e m issio n s. C orrect
m ixtures for e m issio n com pliance and idle quality
have been preset. Plastic idle mixture lim iters have
been installed on the idle mixture screw s to pre­
clude unauthorized adjustment. These idle lim iters
are not to be removed unless made necessary by
som e major carburetor repair or replacement which
affects the idle screw adjustment.
POSITIVE CRANKCASE VENTILATION VALVE
R eplace the PCV valve at 24 months or 24,000
m ile in tervals (whichever occu rs fir st). PCV valve
h o se, when rem oved for valve replacem ent, should
be blown out with an air hose to make certain that
it is clean. The PCV valve should be replaced at
FLYWHEEL H O U SIN G
T-9141
Inspect engine front and rear mountings as
part of regular engine m aintenance program . Be
su re all bracket attaching bolts are kept tight.
R efer to ENGINE MOUNTINGS (SEC. 6D) for engine
mounting inform ation.
12 months or 12,000 m iles (whichever o ccu rs first)
when the v eh icle is used under the follow ing con-
ditionsi
• D riving in dusty conditions.
• E xtensive idling.
• Short trip operation at freezin g tem p er­
atures (engine not thoroughly w arm ed up).
POSITIVE CRANKCASE VENTILATION
SYSTEM - HOSES AND CONNECTIONS
The PCV sy ste m should be checked for s a t is ­
factory operation at 12-month or 1 2 ,000-m ile in­
terv a ls using a te ste r such as the AC T ester C T -3.
POSITIVE CRANKCASE VENTILATION
BREATHER OR FLAME ARRESTER
The breather or flam e a r r e ste r should be r e ­
moved and cleaned at 12,000 m ile in terv a ls. Im ­
m e rse in cleaning solvent to rem ove all deposits
and allow to drain before rein stallin g.
MECHANICAL VALVE LIFTERS
Intake and exhaust valves on V6 engines should
be adjusted at 12,000 m ile in tervals.
MANIFOLD HEAT VALVE
In-L ine engines and som e V6 and V8 engines
are equipped with a m anifold heat valve which should
be checked for free operation. A binding valve may
be freed up with G eneral M otors m anifold heat
valve lubricant or equivalent. (NEVER USE ANY
OTHER TYPE LUBRICANT.)
FLYWHEEL H O U SIN G ADAPTER
PLATE
Figure 1 shows the flyw heel housing adapter
plate used with 13-inch clutch on 350 and 366 V8
engines.