A SPECIAL 6 1/2- LITRE BENTLEY
A SPECIAL 6-LITRE BENTLEY A SECOND-HAND CAR OF UNUSUAL INTEREST.
IN pre-war days if you wanted to go fast, you bought a car with a large engine, and the speed you achieved depended largely on how much chassis space you were prepared to sacrifice to the all-important. motor. Engine power, braking systems and road-holding have been vastly improved since those far-off days, but the principle still remains the same, and the Bentley which forms the subject of this article came as a refreshing interlude in the stream of small highrevving cars which haYre, become almost universal nowadays.
The origin of the .car is interesting. It started life in 1927 as a standard 61–litre saloon and confirmed as such until 1934, when it came into the hands of Messrs. H. M. Bentley & Partners, who specialise in Bentley cars ; Mr. H. M. Bentley is of course, a brother of ” ANSI” the originator and designer of the famous marque. Mr. Bentley was approached by a customer who wanted a car on the lines of the short chassis S.S. Mercedes-Benz. ” We can do it,” was the reply, and the car selected was the 64–litre Bentley already referred to. The wheelbase was reduced from twelve feet to ten, the compression of the engine was raised to 5.8, and the induction system was altered to take two Zenith carburetters. The bonnet-line was lowered by fitting a Speed-Six radiator and a sporting twoseater body was fitted, and the overall height dropped further by substituting 18-inch wheels in place of the 21-inch type originally used. The result was a
really striking car, with a performance to match. When the car was started up, the deep rumble from the Brooklands exhaust system and the rattle of the hour-glass ratio implied an engine speed of only 500 r.p.m. Driving our way gently through London traffic, quite an easy matter by reason of the excellent driving position, we were soon On our way to firooklands,
pistons recalled very vividly some of the pre-war cars we have had the chance of driving, but once at the wheel, and out on the road, it proved perfectly docile. Starting off in first gear, the lever could then be transferred immediately to the third ur fourth gear positions, and in the latter we burbled along quite contentedly with ignition retarded, at 15 m.p.h., which, with the special 3 to 1 back axle
the only place where one. can nowadays safely try a car of this calibre. However luck was against us, for the plugs proved unsuitable for high speeds and the best speed we were able to achieve before Misfiring set in was 90 m.p.h. in less than one lap of the Track. Later on, however, we reached this speed on the open road with windscreen raised and on a slightly unfavourable gradient so the stated maximum speed of 102 m.p.h. should be reached fairly easily. The same car .fitted with larger wheels actually put up a standing lap of 81.77 m.p.h. in last year’s M.C.C. meeting, and also a flying lap at 101 m.p.h. Another piece of misfortune was the failure of the rev-counter, and the acceleration chart shown is based on changing up at 45 and 60 m.p.h. instead of the 55 and 80 m.p.h., which calculation afterwards showed were permissible.
Performance on the gears is a valuable asset, but what one looks for on a highpowered car like the Bentley is a tremendous flow of power on top gear. In this we were not disappointed. Changing up at 50.or so, the car fairly steamed away to 75 and beyond and held this figure with just an occasional touch of throttle, and as an instance, starting from the end of the 30 m.p.h. limit on the Henley Fairmile, the car bounded up Bix Hill as though it was all level going. Likewise on a test route over deserted road in the West Country our previous highest speed was easily equalled without any attempt to make use of the car’s maximum, but simply sitting there and letting it maintain its effortless 75. The engine at this speed is running at about 2,800 r.p.m. Few people can settle down behind the vheel of a racing car, with its length of powerful bonnet stretch out in front without a feeling of exhilaration, and this was how we felt about the Bentley. In spite of its size, however, the bonnet did
not prevent one seeing both front mudguards, while there is a real satisfaction in directing this large projectile round corners with the certainty of knowing that if what in front of you gets round, the back will look after itself. The Brooklands silencers give the car an organ-like note which is very stirring in the open country, and yet the car can be run in town without giving offence, but a pair of Burgess or similar pattern silencers would be an asset if much town work is contemplated. The driving position behind an unusually large steering wheel gave one complete confidence in the car, which the steering itself had that definite quality which speaks of fine workmanship, and a caster action which centred the wheel of its own accord after rounding a corner. Cornering with heavy cars always seems to us a technique on its own, and it takes a little time to remember to choose the correct path beforehand. Once this was done the Bentley took them as it were in its stride, with the minimum of effort on the part of the driver, and we proved it
to our full satisfaction in a long chase we had with a solo motor-cycle, a contest which ended comfortably in favour of the car. The suspension proved equally satisfactory on road and track, and the weight distribution was such that the tail slid slightly with really violent cornering, though the six-inch tyres seemed to exert such a powerful grip that it was hard to provoke even a squeak. The brakes are of the mechanical type, fully com pensated, and with a vacuum-servo motor to aid the driver, came on powerfully with a light use of the brake pedal. They
proved very satisfactory, as can be appreciated from the braking figure of 52 feet from 40 m.p.h. Gear-changing as would be expected, is needed much less on the Bentley than on smaller cars, but the maxima of 80, 55 and 35 can be employed with effect when needed. The gear-changing requires a fair amount of practise before a noiseless change can be guaranteed, more by reason of the low engine speeds than any inherent difficulty of manipulation. The gearbox was made well before the time of ” silent-thirds,” but the hum from the gears is quite unobjectionable. The back axle is fitted with special straight-tooth racing bevels, and these actually make more noise than the gearbox pinions,
but in view of the increased factor of safety for track work, their use is justified. The overall gear ratios are 3.03, 3.88, 5.51 and 10.2, the “low top-gear ratio” as Messrs. H. M. Bentley call it, being
installed to give a good top-gear performance on the road, and limits the allout speed to 102 m.p.h., but if the car were used for track work, this could be raised by fitting larger rear wheels.
The car was rebuilt in April, 1934, and has since done 10,000 miles.
The engine runs quietly, smoothly, and without any periods, and the carburetter is satisfactory throughout the range. Two plugs per cylinder are used, with coil and magneto ignition. It is worth recalling, perhaps, that two inlet and two exhaust valves per cylinder were used on the large six-cylinder engine, giving a long period of service without needing for re-grinding.
The lighting and ignition system is controlled with the minimum of complication through single-pole switches on the dashboard, and the Marchal headlights which give an even spread of light behind which one can drive in comfort at 70 m.p.h., have a dipping mechanism controlled through a foot-switch. The two-seater body fitted was attrac
Something like an engine ! This 63-litre Bentley differs from standard in having two Zenith carburetters. Read about its performance on the road in the accompanying article. ft’s a real motor-car.
Another feature peculiar to these engines was the ingenious drive for the overhead camshaft which was effected through a system of rods and eccentrics from the rear end of the crankshaft. Two Centopulse electric pumps are used to supply fuel from the 16-gallon rear tank. The petrol consumption worked out at 10 m.p.g., and we found Pratts Ethyl well suited to the engine’s requirements. 9 5 10 15 20 25 30 35 40 45 SECONDS 90 80 70 GO
50 a. 40 30 20 10
tive in line and eminently suited to high speed on road or track. The same unfortunately cannot be said for the windscreen, which was too low, too far away and would also have been improved by being given a backward rake. However this matter could be rectified at small expense. The two front seats had peculiar high narrow bucket backs, which absolutely prevent side sway when cornering and are set at an appropriately alert angle. The wings were small and readily removed. The only luggage space provided was a small locker behind the seats, and this is also used. for stowing the hood and its collapsible frame.
As a super-fast road, car for summer touring in England or abroad this Special Six Bentley, would be ideal, while its equipment has been determined largely with a view of its also being raced at Brooklands or elsewhere. Actually with more complete wings and weather protectiOn there. is no reason why it should not be used all the year round, and anyonewho buys it is assured of a car which will both create an impression and justify it. The car is for sale, the price being £675, and we have to thank the present owners Messrs. H. M. Bentley and Partners of 3, Hanover. Court, London, W. 1, for their courtesy in permitting us to test it.