Chevrolet Light - Page 31

stalled wh en ad ju sting the engine speed as this is the only pr~
tection against tampering by unauthorized persons .
Care and Maintenance. The attaching bolts shou ld be kept tight
and the governor should be k ept clean externally. If the gov-
erno r requires any service attention the truck should be taken
to an authorize d service sta tion.
Ignition System
Description. The ignition syst em consists of the ignition switch
to
open and close th e circuit , the coil to ind uce high voltage,
the distributor to make and break the low tension circuit and
di
str ibute th e high tension curren t to the correct spark plugs,
the spar k plugs to provide the spa rk in the combustion cham-
ber and the necessary wiring
(fi g. 35). The battery is the
source of cu rrent for the ig-
nition sys tem when starting
the engine or ope ra tin g at
idling speed. Th e generator
furnishes the ignition cur r ent
at higher speeds.
The distributor mounting
provides a means of properly '----::--,,;-:---::;- --::-::-- ---'
setting the in itial ignition
timing. The s park advance for various speeds and loads is
controlled au tomatically by gover nor weights and vac uum con -
tr ol in th e dis~tibutor. Th e vacuum control is connected to
the carburetor.
Th e octane selector at the rear of the distributor m oun ting
provides a
means of advancing or retarding the ignition timing
for
the grad e of fuel being used.
Che vro l et trucks u se 14 millimeter s park plugs. Th ese plu gs
operate at a more satisfactory t empe rature as they warm up
more quickly, yet run at a l ower temperature und er seve re
operating conditions.
Carc.
Th e ba tt ery and generating syst em must be kept in good
ope
ra ting condition in order to o btain satisfactory operation of
th e ignition syst em. All wiring co nnect ions in the ignition cir -
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