Chevrolet 1970 Owner's Manual page 62

Positive Crankcase Ventilation Valve
(PCV) are important to control hy-
dro-carbon and CO emissions within
government legislated levels. These
adjustments and an operational check
of the
pev
valve should be made at
the first oil change (4 months or 6,000
miles, whichever occurs first) . The
aQove fuel and electrical system checks
al~o
are included in engine tune-ups
;Which are recommended at one year
or 12,000-mile intervals.
Positive Crankcase
Ventilation Valve
Replacement
Crankcase vapors and other impuri-
ties can cause malfunction of the
crankcase ventilation valve. Regular
replacement of the PCV Valve is rec-
ommended at 12-month or 12,000-mile
intervals.
G.M. Evaporation
Control System
The Evaporation Control System
requires only periodic canister filter
servicing.
Every 12 months or 12,000 miles,
whichever occurs first, (more often
under dusty conditions), the filter in
the base of the canister must be re-
placed and the canister inspected.
Engine Oil Filter
The engine oil filter should be re-
placed at the first engine oil change
and every second oil change there-
after. This recommendation is based
on the use of an engine oil which meets
the requirements indicated in the sec-
tionon "Engine Oil Recommenda-
tions," and the use of a quality oil
filter. AC oil filters provide maximum
engine protection.
Manifold Heat Control Valve
Every 6000 miles or 4 months, check
heat control valve for freedom of op-
eration. If shaft is sticking, free it up
with a.M. Manifold Heat Control
Solvent or its equivalent.
Drive Belts
Every 6000 miles or 4 months-In-
spect drive belts for wear, fraying,
cracking, and tension. Belts which are
in poor condition should be replaced
immediately.
59
Check tension by applying moderate
thumb pressure midway between pul-
leys. If the center to center distance
between pulleys is 13 to 16 inches the
belt should deflect
¥2
inch. If the cen-
ter distance is 7 to 10 inches, the belt
should deflect
1/4
inch. Loose belts
should be retensioned to give correct
deflection.
Air Cleaner
Paper Element Type - First 12,000
miles, inspect element for dust leaks,
holes or other damage, replace if
necessary. If satisfactory, rotate ele-
ment 180 0 from original installed po-
sition. Replace element at 24,000
miles. Element must not be washed,
oiled, tapped or cleaned with an air
hose.
CAUTION: In addition
to
its function 01
filtering air drawn into the engine through
the carburetor, the air cleaner also acts
as a flame arrester in the event the engine
backfires. The air cleaner should be
installed at all times unless temporary
removal is necessary during repair
or
maintenance of the vehicle, because
backfiring could cause fire in the engine
compartment.