Hercules JXD - Page 16

TM
9–1706
HERCULES JXD GASOLINE ENGINE FOR SCOUT CARS
9
( 2 ) Insert an accurate compression gage in spark plug hole and
crank
engine
a few turns with
starting
motor ,
noting highest
gage
reading . Do this at each cylinder .
( 3 ) Compression should be the same in each cylinder within 5
pounds .
b . Procedure . — If compression is found to be correct in all cylin
ders , proceed with the tune - up in the following order :
( 1 ) Spark plugs .- ( a ) Spark plugs should be Champion , model J8 ,
type 14MM , or other make of same model and type .
(
6
)
Clean
the
plugs
thoroughly
.
(
c
)
Inspect
closely
for
cracked
porcelain
.
( d ) Set electrode gap between 0.025 and 0.028 inch . Use a round
feeler gage . Bend side electrode when regapping .
( 2 ) Battery
and
ignition
cables
.-
(a ) Clean
both
ends
of
each
bat
tery
cable
thoroughly
.
See
that
connections
are
tight
.
(
6
)
Inspect
ignition
system
high-
and
low
-
tension
cables
.
Ter
minal
on
each
end
must
be
clean
and
tight
.
If
insulation
shows
evi
dence
of
deterioration
,
cable
should
be
replaced
.
( 3 ) Distributor .- ( a ) Remove distributor cap and inspect it care
fully for cracks and burned posts .
( 6 ) Remove rotor , clean contact point , and make sure spring con
tacts secondary terminal .
( c ) Clean distributor points with a flat point file . Inspect care
fully and replace if cleaning does not remove pits and burns . Never
use emery cloth to clean points .
( d ) Adjust points with feeler gage to provide 0.018 to 0.020 inch
clearance . Be sure that breaker cam is in position to have points fully
separated .
( e ) Check condenser . A weak condenser usually results in burned
breaker points . A good check is the comparison test , replacing the
old with a good condenser and observing for contrast in the spark .
The spark from a faulty condenser will form an are or drag between
the
points
.
( f ) Check ignition coil with coil tester . Replace weak coil .
( 4 ) Ignition tuning . – Check ignition timing to be sure that No. 1
cylinder is firing according to flywheel markings . This is done by
attaching one end of a neon timing light to No. 1 spark plug and
grounding the other end . Run the engine at an idle speed and note
whether
the neon
flashes coincide
with the
markings
on the
flywheel
.
Distributor can be retarded or advanced until neon flashes are per
fectly synchronized with the flywheel markings .
9