Chevrolet BEAUVILLE SPORTVAN G10 SERIES, Руководство по обслуживанию

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ENG IN E 6-2
Fig. 1—C heckin g C om pression
TEST COMPRESSION (FIG . 1)
The com pression check is im p o rta n t because an engine w ith
low or uneven com pression can n o t be tu n e d successfully. I t is
essential th a t im p ro p er com pression be co rrected before p ro ­
ceeding w ith the engine tu n e up.
1. Rem ove air cleaner and block th ro ttle and choke in wide
open position.
2. H ook u p sta rter rem ote co n tro l cable and insert com pres­
sion gauge firm ly in spark plug port.
C A U T IO N : Whenever the engine is cranked re­
m otely at th e starter, w ith a special jum per cable or
other means, the distributor prim ary lead must be
disconnected fro m the negative post on the coil.
3. C rank engine th ro u g h a t least four com pression strokes
to o b ta in highest possible reading.
4. C heck and reco rd com pression o f each cylinder.
5. I f one o r m ore cylinders read low or uneven, inject about
a tablespoon o f engine oil on to p o f pistons in low
reading cylinders (th ro u g h spark plug p o rt). C rank engine
several tim es and recheck com pression.
• I f com pression com es u p b u t does n o t necessarily
reach norm al, rings are w orn.
• If com pression does n o t im prove, valves are b urnt,
sticking or n o t seating properly.
• I f tw o adjacent cylinders indicate low com pression
and injecting oil does n o t increase com pression, the
cause m ay be a head gasket leak betw een the
cylinders. Engine coolant an d /o r oil in cylinders
could result from this defect.
N O T E : If a weak cylinder cannot be located w ith
the compression check, see "C ylin der Balance test"
under "A d d itio nal Ciiecks and Adjustm ents" in this
section.
SERVICE & IN STA LL SPARK PLUGS (FIG . 2)
1. Inspect each plug individually for badly w orn electrodes,
glazed, broken or blistered porcelains and replace plugs
w here necessary.
2. Clean serviceable spark plugs th oroughly, using an
abrasive-type cleaner such as sand blast. File the center
electrode flat.
3. Inspect each spark plug for m ake and heat range. All
plugs m ust be o f the same m ake and num ber.
4. A djust spark plug gaps to specifications using a round
feeler gauge.
C A U T IO N : Never bend the center electrode to
adjust gap. Always adjust by bending ground or side
electrode.
5. If available, test plugs w ith a spark plug tester.
6
. Inspect spark plug hole threads and clean before in­
stalling plugs. C orrosion deposits can be rem oved w ith a
14 m m . x 1.25 SAE spark plug tap (available through
local jobbers) or by using a small wire brush in an electric
drill. (Use grease on tap to catch chips.)
C A U T IO N : Use exptrem e care when using tap to
prevent cross threading. Also crank engine several
times to blow out any material dislodged during
cleaning operation.
7. Install spark plugs and torque to specifications.
N O T E : T iie follow ing are some o f the greatest
causes o f unsatisfactory spark plug performance.
• Installation o f plugs w ith insufficient to rq u e to
fully seat.
• Installation o f the plugs using excessive torque
w hich changes gap settings.
• Installation o f plugs on d irty seat.
C H E V Y V A N SHO P M A N U A L