RUNNING INSTRUCTIONS
During the first 500 miles (800 km.)
DO NOT exceed 45 m.p.h. (72 km.p.h.).
DO NOT operate at full throttle in any gear.
DO
NOT
allow the engine to labour in any gear.
Towing eyes
When it is necessary to tow a vehicle, use the towing eyes if
fitted .
High-compression engine (8'9 : 1)
This engine is a highly developed unit and it is essential that you should know
something about the specialized maintenance it requires if you are to maintain
it at the peak of its mechanical efficiency. Special recommendations on the
sparking plugs, ignition settings, and fuel to be used are given by the manu-
facturers, and it is stressed that failures are bound to occur
if
these are not
strictly adhered to. Particular care is needed with this engine owing to its high
compression ratio , which makes it extremely sensitive to variations in fuel,
ignition timing, and the heat range of the sparking plugs.
In
lower-compression engines a much wider range of fuels can be tolerated
with
out
causing serious damage to the engine, and ignition settings will stand
variations of a reasonable amount. Also, even if the incorrect sparking plugs
are used, no more damage may be incurred than burnt-
out
plugs or leaky valves.
But with an engine having a very
high compression ratio the range of fuels,
sparking plugs, and ignition settings is much narrower and it is essential that the
mixture
should always be correct, and particularly never overweak at maximum
load or power.
High compression engines are very sensitive to variations in spark advance
(over-advance) and to fuel/air ratio (mixture). Variations in these settings will
increase the combustion temperature, and
if
the variation is excessive pre-
ignition will cause high shock waves, resulting
in damage to the engine.
The engine should be decarbonized at regular intervals as excessive deposits
of ash from the combustion of lubricating oil and fuel can cause pre-ignition
difficulties.
Choice of
fuel
When fitt ed with H .C. engine (compression ratio 8·9 : 1)
The octane number of a motor fuel is an indication given by the fuel technicians of its knock resistance. High-octane fuels have been produced to improve the efficiency of engines by allowing them to operate on high compression
ratios, resulting in better fuel economy and greater power. Owing to the high
compression ratio of the engine, fuels with an octane rating below
98 are not
suitable;
should it be necessary to use a fuel with a lower octane number, the
car must be used very carefully until the correct fuel can be obtained.
It
is necessary to use Super grade fuels in the 100-octane rangeunless Premium
fuels of minimum 98-octane (Research method) are available.
When fitted with L.c. engine (compression ratio 8·1 : 1)
Premium fuels of minimum 93-octane (Research method) up to 97 octane are
required, with preference to 95/97.
Super grade fuels in the 100-octane range can be used
if
preferred.
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