Sparking Plug
The sparking plug is of great importance to satisfactory engine performance, and
every care should be taken to fit the correct type when replacements are necessary.
There is little to be gained by experimenting with different plugs as the make and
type fitted by us as official factory equipment is best suited to the requirements of the
motor. This is Champion type No. L10S, as illustrated in Fig. 4. (N
OTE
:—according
to the new Champion rating this plug will be designated No. L7).
F
IG
. 4.
The sparking plug.
Remove the sparking plug every 1,000 miles (1,500 Km.) or so for inspection.
If the carburation system is in correct adjustment the sparking plug points should
remain clean almost indefinitely. An over-rich mixture from the carburetter will,
however, cause the formation of a sooty deposit on the points and, later, on the plug
end face (as upper view, Fig. 4). If therefore such a deposit is found, clean it off
carefully and check your carburetter. Too high a proportion of oil in the petroil
mixture will also cause plug fouling (see page 9). The continued use of leaded fuel
may also eventually produce a deposit on the plug—this time of a greyish colour.
F
IG
. 5.
Setting the plug points.
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