Chevrolet 1970 Owner's Manual page 86

Evaporation Control System (Required only
in California)
General Motors vehicles sold in California are equipped with
an Evaporation Control System. This system is designed to min-
imize the escape of fuel vapors to the atmosphere. Included in
the system are a special fuel tank, liquid-vapor separator, car-
bon canister, canister purge hoses, and carburetor modifica-
tions. Fuel vapors which would otherwise escape to the atmos-
phere are directed into the carbon canister. The carbon absorbs
the vapors and stores them. The vapor is removed from the
canister during periods of engine operation as manii,old vacuum
draws the vapors
into
the engine and burns them. The Evapo-
ration Control System requires only periodic canister filter
servicing. See Service Recommendations.
Note: The General Motors Evaporation Control System is designed to control
evaporation losses from your car under all normal conditions using 9 lb.
Reid Vapor Pressure fuel specified by California test requirements. However,
if you should use fuel of abnormally high volatility for existing temperature
conditions, you may detect a gasoline odor during or after driving in heavy
traffic. If you find this objectionable, you may obtain relief by using a lower
volatility fuel.
B4
For Cleaner Air-Better
Engine Performance-Follow these
Periodic Service Recommendations
Interval
System
Service
At first 011 change Positive crankcase
Check for eJo,!ter
o~eratlon.
4 months or 6,000 ventilation (PCy) inspect PC iller in Air Cleaner
miles (whichever If so equipped.)
occurs tlrst)
Controlled Combus- Set Idle speed, Ignllion lim ing and
tlon System (CCS)
fUel mixture to specifications on
decal under hood.
Air InJection Reactor Same as CCS
(AIR)
At subsequent 011 Positive Crankcase Inspect crankcase ve ntilation
changes-every Ventilation (PCy) filter-replace if nacessary.
4 months or 6,000 Replace at least
miles (whichevar
occurs first)
every 24,000 miles.·
Every 12 mos. or Positive Crankcase Replace PCV valve. Inspect all
12,000 miles
Venlliation (PCy) hoses, and tltlings. Replace
(whichever occurs or clean as necessary.·
tirst)
Controlled Combus- Set Idle speed, ignition liming.
lion System (CCS) and fuel mixture to specifiCations
on decal under hood."
Air Injection Reactor
Same as CCS.·· Also inspect
(AIR)
all hoses and tittlngs for proper
connection and drive belt for wear
and tension.
Evaporation Control Replace filler in base of
System
canIster and inspect canisler.
*
Note: Never replace fuei tank cap
with other than the specified
cap.
-Replace fillers more frequently under dusty conditions.
.... These ad;uslments are also Included as part 01 the quallly tune-up
recommended at the same Intervafs.