The Wolseley Straight Eight

(from The Motor of January 9, 1946)

One might almost term 1928 the "straight-eight year", for at that time the multi-cylinder engine was certainly in the ascendant. In America, 30 per cent of the 1928 models had eight-in-line engines, and in this country the vogue was spreading, not only amongst high performance sports and luxury cars, but in the medium-price field as well. Designers were keen to exploit the flexibility, smooth running and silence of the eight-cylinder engine, in spite of its increased mechanical complexity, and British manufacturers did not neglect this line of development.

Wolseley Motors, Ltd., followed the lead set by Beverley-Barnes in offering a straight-eight which not only had a moderate engine capacity but which was by no means a high-priced car; it appeared at the 1927 Olympia Show and was also represented at the Paris Salon in the form of Morris-Leon-Bollee, the latter car being of virtually identical design. Appearing when it did, the straight-eight Wolseley was one of the first models made under the Nuffield regime, although it must have been designed prior to his arrival. It was, indeed, a development of the well-known 2-litre six, having the same bore and stroke, and using many interchangeable components. The engine had a bore and stroke of 65 by 101 mm, giving a swept volume of 2,700cc or less than 350cc per cylinder, the rated horse-power coming out at 21. Cylinder block and crankcase were one casting; light-alloy pistons and Duralumin connecting rods were used.

In order to obtain balance as good as that enjoyed by a six-cylinder engine, the Wolseley designer chose the 2-4-2 crankshaft arrangement, rather than the 4-4 layout, the balance of which is actually inferior to that of a six. The crankshaft excited considerable comment for it ran in 10 plain bearings with a vibration damper at the front, and it was in two halves, so that the timing gears could be accommodated centrally. These skew gears drove a vertical shaft, with another gear at its upper end meshing with a gear in the centre of the two-piece oh camshaft. The vertical shaft also drove two cross shafts by means of further gears, the off-side shaft protruding from the cylinder block to engage a vernier coupling from which was taken the right-angle distributor drive, while the dynamo was bolted at right angles to the block on the near side and driven directly from the other cross shaft.

Although ohc valve gear was used, every endeavour was made to ensure quiet operation, corrugated washers holding the timing gears in mesh and eccentric rockers being employed for the tappet adjustment. The valves were vertical. Lubrication was looked after by a gear-type pump, operated from a shaft extending downwards and driven from the gear on the centre of the crankshaft. The system incorporated an external oil cleaner through which the sump content (nearly two gallons) was passed eight times an hour. The valve gear was supplied through the hollow rocker tubes.

Cooling was assisted by a water impeller, driven, like the fan, by Whittle belt from the front of the crankshaft. The length of the engine necessitated a two-branched water connection on the off side of the block.

The 2-4-2 crankshaft arrangement gives rise to awkward induction problems, because it is not possible to treat the engine as two four-cylinder units and use one carburettor for each. Nevertheless, with a firing order of 1, 3, 7, 4, 8, 6, 2, 5, the Wolseley designer contrived to use a comparatively unheated manifold and a single horizontal S.U. carburettor. The manifold was square in section and located on the near side directly above the ribbed exhaust manifold, the latter having a vertical off-take at each end. Four inlet branches fed downwards into siamesed ports and the carburettor had an air-cleaner set transversely above the valve cover. Fuel feed was by Autovac from a 14-gallon rear tank.

The rest of the car was perfectly straightforward. In unit with the engine was a single-plate clutch and a four-speed gearbox, while final drive was by open shaft to a spiral-bevel back axle.

Suspension was by half-elliptic springs damped by Armstrong friction shock absorbers. Steering was by worm and wheel and the car had six brakes-the hand lever operating its own pair of back shoes, while the pedal acted on all four wheels via compensated cables. The front brakes were of Rubery type. The gear lever was centrally disposed, but the hand brake lay almost horizontally on the right. All three pedals were adjustable.

The chassis was intended to carry commodious coachwork, having a wheelbase of 9 ft 7 ins and a 4-ft 8-in track; for this reason the top-gear ratio was 5.57 to 1, rather lower than might be expected with an eight-cylinder engine. The other ratios were 8.6, 13.0 and 21.4 to 1, but on later cars a 5.0 to I rear axle was fitted, which gave indirects of 7.72, 11.65 and 19.2 to 1. Artillery wheels carried 21 by 5.25 tyres and the chassis was not unduly heavy, weighing about 19 cwt.

When first announced, the 21/60 chassis cost £550, open two and five seaters being listed at £695, and a saloon at £750. The last-named had a maximum speed of about 70 mph. For 1929, prices were substantially reduced, the chassis to £435, the open cars to £540, and the saloon to £550. At the same time, another 21/60 model, but with six cylinders, and a 4-litre edition of the eight, rated at 32 hp, were introduced. The latter lasted only two seasons, but the 21/60 eight-cylinder was manufactured up to 1931. In its time it was an exceptionally smooth and flexible car, but the economic depression hardly favoured the large vehicle, and six-cylinder engines later drove out the medium-sized eight.