Page 14 - Bentley Mark VI & R-Type

2
The standard air filter with its drum-shaped silencer was of the oil-wetted
steel mesh variety, though in 1949 for some markets perceived to have
dusty environments an oil-bath air filter was introduced. This type of filter
was fitted in conjunction with the usual air silencer – the horizontal drum
– and was sufficiently heavy to warrant the additional supports attached
to the cylinder head seen in the illustrations on the previous page.
COOLING SYSTEM
ON WATSON FINE BO
The Bentley Mark VI and R-Type, as well as the Rolls-Royce Silver Dawn,
had fixed radiator shutters and a coolant circulation thermostat to regulate
engine temperature. The thermostat was unconventional in having two
valves, one above the other. With the engine cold, the coolant circulated
around the engine via the radiator by-pass passages. As the engine warmed
up the upper valve opened to circulate coolant through the radiator. At the
same time the lower valve closed to shut off the radiator by-pass so that all
coolant passed through the radiator once it reached operating temperature.
Both the Bentley and Rolls-Royce ‘radiators’ that are such famous external
distinguishing features of the cars are in both cases a cosmetic shell
surrounding the actual radiator. Likewise, the water filler cap on which
structure at the time.
DALTON WATSON FINE BOOKS
the Winged-’B’ or Spirit of Ecstasy mascot is mounted is a dummy, with
the actual water filler located under the bonnet on the left-hand side. The
Bentley radiator shell was a chrome-plated brass pressing, while that of the
Rolls-Royce Silver Dawn was hand-made by specialised craftsmen from
stainless steel sheet using nothing more advanced than an old-fashioned
soldering iron – the only practical way of making such a sharp-edged
The earliest Mark VI radiator shells had ten vanes on each side of the grille.
This close spacing of the vanes was found to allow insufficient cooling air
through the radiator and from B320CF the angle of the vanes was changed
to increase air-flow. Many earlier cars were retrospectively modified.
From B163DZ onwards the number of vanes was reduced to nine per side
and, from B270DA onwards, the frontal area of the radiator matrix was
increased. The final change to the grille occurred from R-Type B210TN
when the Company saw fit to add a central bar.
The Bentley Continental radiator shell was similar to that of the later
Bentley Mark VI but reduced in height.
The Rolls-Royce Silver Dawn was the first Rolls-Royce car to have fixed
radiator shutters, of which there were eleven per side.
© DALTON WATSON FINE BOOKS
ABOVE: The dual-valve coolant
circulation thermostat fitted to all
models dealt with in this book. As
the coolant warmed the upper valve
opened, circulating coolant through
the radiator and engine. At the same
time the lower valve closed, shutting
off the radiator by-pass passages. For
obvious reasons, therefore, a modern
single-valve thermostat should on
no account be fitted to any post-war
six-cylinder engine dealt with in this
book, nor should any such engine be
run without a thermostat, as in either
case the radiator by-pass will remain
fully open, allowing a proportion of
the coolant to not circulate through the
radiator and therefore not be cooled.
LOWER: Short-boot Silver Dawn
in Australia.
© DALTON WATSON FINE BOO
SDB26, delivered in Melbourne in
May 1951, returned to its country of
origin for a few years but is now back
OPPOSITE PAGE: The early rearward-
leaning (top) and the later forward-
leaning Winged-’B’ mascots supplied
with Bentley Mark VI & R-Type cars.
The third photograph from top shows
the ‘kneeling’ pattern Spirit of Ecstasy
mascot fitted to Rolls-Royce Silver
Dawns. The bottom illustration shows
the Luvax-Bijur combined reservoir
and pump for the centralised chassis
lubrication system fitted to all models
in this book.
ALTON WATSO
Bentley Mark VI & R-Type
78