ENGINE
Fig.
41
in both operations in order not to
injure electrode or insulator tip.
The
threaded section of p1,ug shell is often
neglected in plug cleaning, even
though, like the gaskets, these threads
form a means of heat dissipation.
When threads are coated with carbon,
it retards the even flow of heat to the
cooling medium, thereby causing over-
heating. (When installing plugs, this
simple procedure will ensure no
binding of threads and avoid
un-
necessary use of plug spanner.) Screw
the plug down by hand as far as
possible, then use spanner for tighten-
ing only. Always use a box spanner to
Svarkine Plue Gaskets in various con-
avoid possible fracture of the insulator.
dhions.
sumption. It may be, however, that a
plug of a
"
colder
"
type is required.
(f)
After cleaning, examine plugs for
cracked insulators or insulator nose
worn away through continued pre-
vious cleaning. In this case we
should recommend that the plugs
have passed their point of useful life
and new plugs should be installed.
Look .for a deposit on the insulator,
under side electrode, which may ac-
cumulate heat and act as a
"
hot spot
"
in
service.
(g)
After cleaning and blowing surplus
abrasive out of shell recesses and off
plug threads by means of
"
blow out
"
nipple-xamine threads for carbon
accumulation. Use a wire brush to
remove carbon and clean the threads.
A wire buffing wheel may also be
utilised
;
however, use reasonable care
Champion Series
"
700
"
Cleaner and
Tester Unit.
Next, we are ready for resetting the
electrodes (Fig. 44). Remember that
electrode corrosion and oxides at gap
area vitally affect spark efficiency. The
cleaner can remove the oxides and
deposits from the insulator, but be-
cause of gap location, the cleaner
stream cannot always reach this area
with full effect, also, the tenacious
adhesion of corrosion, etc., would
require too much subjection to clean
blast for removal. Therefore, when
plugs are worthy of further use, it is
sometimes good practice to dress the
gap area, on both centre and side
electrodes, with a small file before
resetting to correct gap.
Resetting of electrodes should be
Dart
A
Blistered Insulator.
of service during useful life of-the
39
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