Subaru 1600 Service Manual page 699

2) Removal and Installation
1) Remove the spark plug cords by
pulling the boot, not the cord itself.
2)
Remove spark plugs.
3) When installing the spark plugs
on the cylinder head, use a spark plug
wrench.
Torque
(Spark plug)
NOTE:
20-29N·m
( 2 - 3 kg-m,
14 - 22 ft-lb)
The above torque should be only
applied to new spark plugs without
oil on their threads.
In case their threads are lubricated,
the torque should be reduced by
approximately 1/3 of the specified
torque in order to avoid their over-
stressing.
4) Connect the spark plug cords.
3) Inspection
I) Check the electrodes and inner
and outer porcelains of plugs, noting
the type of deposits and the degree of
electrode erosion.
• Normal
Brown to grayish-tan deposits and
slight electrode wear indicate cor-
rect spark plug heat range.
, I
I I I
I
ELECTRICAL SYSTEM
A9-164
Fig. 15-121 Normal
• Carbon fouleo:
Dry fluffy carbon deposits on insu-
lator and electrode are mostly
caused by slow speed driving in
city, weak ignition, too rich fuel
mixture, dirty air cleaner, etc.
It
is advisable to replace with plugs
having hotter heat range.
A9-165
Fig. 15-122 Carbon fouled
• Oil fouled:
Wet black deposits show excessive
oil entrance into combustion
chamber through worn rings and
pistons or excessive clearance be-
tween valve guides and stems. If
same condition remains after repair,
use a hotter plug.
15-36
I I
I
" I
A9-166
Fig. 15-123 Wet spark plug with oil
~
Overhea ting:
White or light gray insulator with
black or gray brown spots and
bluish burnt electrodes indicate en-
gine overheating. Moreover, the ap-
pearance results from incorrect igni-
tion timing, loose spark plugs,
.\'fong selection of fuel, hotter range
plug, etc. It is advisable to replace
with plugs having colder heat range.
A9-167
Fig. 15-124 Overheating
4) Cleaning and Regapping
Clean spark plugs in a sand blast
type cleaner.
Avoid excessive blasting Clean and
remove carbon or oxide deposits, but
do not wear away porcelain.
If deposits are too stubborn, dis-
card plugs.
After cleaning spark plugs, recondi-
tion firing surface of electrodes with
file. Then correct the spark plug gap to
1.0 to 1.1 mm
(0.039
to 0.043 in)
using a gap gauge.