Motoring Notes
The Six-Cylinder Bentley
" Big " Beaky, as it is generally called, is a recent model built much on the lines of the popular four-cylinder car which has been on the market for sonic years, but it has been designed with a different purpose, namely, to carry larger and heavier bodies than the small model, but without any idea of " Super Sports." Excessive speed has not been aimed at, but it will reach the eighty mark under full load; which is quite fast enough for all reasonable purposes. The exhaust is hardly noticeable when driving and no " cut-out " is fitted, the main idea being smooth and quiet running combined with good acceleration.
The up-to-date engine of 100 by 140 min. is unusual in having four valvc3 to each cylinder, and two magnetos with a synchronized variable advance. These magnetos arc most accessible, and are controlled by separate switches enabling the engine to be run on either, or both, at will. I like the design of four valves to each cylinder because thk allows greater cooling surface, and enables lighter valve springs to he used. The effect on the engine is freedom from carbon deposit to such an extent that the makers do not contemplate decarbonization and valve grinding under 20,000 miles. Instead of employing gears the overhead camshaft is operated by three coupling rods, which, in actual operation, arc very:. silent. Both the camshaft and the crankshaft have eight bearings, the latter having a damper fitted at the forward end. All the valve mechanism is fully enclosed, and oil is forced under pressure throughout, except in the ease of the pistons and gudgeon pins, where lubrication is by splash.
For town driving in particular, a light clutch is a comfort,
and for this reason, and because its mechanism is aidomatically lubricated, the Bentley clutch is deserving of praise. The care and oiling of many clutches is normally a somewhat tedious affair which in consequence is often neglected, and. this point introduces the question of the general care of the- chassis as a whole.
There are only three grease cups on the ear, one on the Water pump, and two on the dynamo, all of which are accessible. For the general lubrication a Tecalemit oil-gun is employed, but it is not expected that this gun need be used more than four times in a year of normal mileage. The makers make a special feature of this, which, from the point of view of the comfort of an owner-driver, has much to recommend it. To be able to take a car away for three months at a time, with the knowledge that the filling of three grease cups com- prises the entire necessary lubrication of the chassis, is a factor which cannot fail to attract.
Four-wheel brakes are fitted as standard, with two additional
hand-operated brakes on the rear wheels. On the ear I drove the brakes were not servo-assisted, but nevertheless were quite. efficient in action. In future, however, the Dewandre system' of servo vacuum is to become a standard fitting, and I think it may safely be assumed that the braking will be highly efficient.
Steering is very light and is self-returning. I thought that there was excessive play in the wheel which I used, but was informed that this could be reduced if desired.
Semi-elliptic springs are used throughout, assisted by Hartford shock-absorbers. I found the springing was•some- what harsh at low and medium speeds, but at high speed the . road shocks were very well absorbed. There is a road clearance of nine inches all over, but in spite of this the car holds the road very well at high speed, and I was agreeably. surprised at the quietness of the engine and absence of valve clatter or exhaust noise. The maximum speed on top gear is a shade over 80 m.p.h., and the light steering to which I have made previous reference, a wide lock, and careful distribution of weight make the car pleasant to handle at all paces. No bodywork is standard, but to suit different types the
chassis wheelbase is supplied in three sizes, varying from eleven to twelve and a half feet, the ratios of the spiral bevel drive being varied to suit. Gear-changing is not often necessary on the road because, even on top gear, the car is very docile and easy to handle in traffic, and the power is such that most hills can be successfully negotiated without a change down. If, however, a change down is made the note is not harsh or unpleasant. Personally, I found the gears a little awkwardly placed, and I should prefer a larger- sized gate.
So great, I am told, is the care taken to ensure that only the best of materials and workmanship is employed that the makers -feel fully confident in giving a five years' guarantee with this chassis. PELHAM COCHRANE.
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• The Motoring, Editor will be glad to answer questions or draw -up itineraries for readers.
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