Chevrolet 10 Series 1970, Service Manual

Page: 425 / 671

ENGINE-ELECTRICAL 6Y-33
F ig . 2 0 i —E ight C y lin d e r Engine D is trib u to r
NOTE: The brackets a re numbered to show the
c o rre c t installation. W ire s must be installed as
indicated to preven t c ro s s firin g .
8. Connect vacuum line to d istribu tor and distributor
p rim a ry w ire to coil term in al.
9. Start engine and set tim ing as d escrib ed under
Tune-Up in Section 6.
SPARK PLUGS
C leaning and Regapping
Clean the spark plugs thoroughly, using an a b ra sive -
F ig . 2 l i —S e ttin g Spark Plug G a p
type clean er. If the p o rcela in s a re badly gla zed or
b lis te re d , the spark plugs should be replaced. A ll spark
plugs must be o f the same make and number o r heat
range. Use a round fe e le r gauge to adjust the spark plugs
gaps to sp ecification s (fig . 2l i ) .
CA U TIO N : B e fo re adjusting gap, file center
electrod e flat. In adjusting the spark plug gap,
n ever bend the center electrod e which extends
through the
p orcela in center. A lw ays
m a k e
adjustment by b e n d i n g the ground o r side
electro d e.
Installation
Install the spark plugs in the engine with new gaskets
and torque to sp ecification s. If torque wrench is not
ava ila b le, tighten plugs fin ger tight and 1/2 turn m ore.
P lu gs a re o f a 14 m illim e te r s ize and care must be e x e r ­
cised when installin g or the gap setting may be changed.
TRUCK ENGINE OVERSPEED W A R N IN G SYSTEM
The purpose o f this oversp eed warning system is to
warn the d r iv e r o f e x c e s s iv e engine speed in an o ver-ru n
condition (such as during down hill operation when the
w h eels may begin to d riv e the engine) and thus enable
steps to be taken to c o rre c t the condition.
The system (fig . 22i) consists o f an am ber jew eled
warning lamp mounted in the cab, a vacuum sensing
sw itch in the spinner go vern o r vacuum line, and a w arn­
ing lamp burnout checking circu it. These components
operate in conjunction with the 2G Engine G overn or
(Vacuum Spinner T yp e) d escrib ed in Section 6M o f this
Shop Manual.
In operation, when the engine reaches its governed
speed (4000 rpm with standard tran sm ission o r with
CHEVROLET TRUCK SERVICE MANUAL