The Knight-Rover engine

The connecting rods for the two cylinders are side by side on the same crank pin, making firing points equidistant. The engine is mounted directly on the chassis frame. It can be seen from the illustration the rearmost bracket rolls over the flywheel, making the rear mountings much further apart from the front set than would be allowed by mounting the engine direct from the very short block. Magneto, distributor and water pump are driven by skew gear from the front of the crankshaft, as are the pinions and chains which drive the valve shafts operating the sleeve valves. The two-jet carburettor incorporates a silencer on its air intake. The first jet is used only at starting or at idle.^[2]

A supplementary air supply controlled by a foot pedal operated at will by the driver provides an oil mist from inside the engine's crankcase to lubricate the tops of the valve sleeves. A three-plunger pump driven by the valve shaft forces oil from the sump to troughs under and in the path of the big ends. With each revolution the big ends dipping into the troughs throw oil to all parts of the engine. The dashboard has a telltale to warn if the pump is not working properly.^[2]

Chassis

The chassis was entirely new. The metal to metal multi-plate clutch requires no lubrication. Two plates are phosphor bronze, the others are steel. There is a double universal joint (a sliding block allows for withdrawal of the clutch) between the clutch and the gearbox. The gearbox is mounted on a separate underframe; all its shafts run on ball bearings. There are three forward speeds. The propellor shaft is fully enclosed and has a ball and fork joint at its forward end. Final drive is by overhead worm.

the concentric twin brake drums

The brakes are unusual: both hand and pedal levers operate on the back wheels but upon different concentric drums, the outer drum being used by the foot brake. There are semi-elliptic springs front and rear, but at the rear of the plate springs are two coil springs on each side of the car which anchor the plate springs. Drive is transmitted to the frame by the front end of the semi-elliptic plate springs. There are no radius rods.[2]

rear suspension showing coil springs in plan and elevation

Road test by The Motor

The test car was equipped with a four-seated torpedo body. The compact (106-inch) wheelbase left ample legroom for driver and passengers; there was space for luggage behind the front seat in front of the passengers. A spare gallon tin of oil and a tin of petrol was carried on one running board and a picnic hamper was strapped to staples on the running board on the other side, along with a large accumulator to run the electric lamps, all leaving ample room for ingress and egress through either door. "There was a slight tendency (for the rear wheels) to skid on very greasy roads." It was not necessary to add any water to the radiator during the ten days of the test. The Knight-Rover sleeve-valve engine was so silent the driver was often asked if it was running. "Would not hesitate to recommend it". "One of our passengers went off without saying a word and bought a similar car within 24 hours."^[5]

Road test by The Automotor Journal

"A nice smooth running little car". During acceleration there is a low periodic noise as of escaping steam which disappears once under way and the car runs silently. Smooth running requires a very particular adjustment of the ignition and throttle controls. Rover maintains its prejudice against foot-operated accelerators. The engine will pick up from standstill on top gear if the clutch is made to slip a little. There is a very powerful clutch stop which requires a gear change to be made in one rapid movement. If the change is missed it will be necessary to stop the car to engage any gear. If Rover fitted an accelerator pedal it would satisfy all opinions.^[3]

Rover Pilot

Rover Pilot
Pilot with special sports body
Overview
Designer	engine designer B H Thomas
Body and chassis
Body style	chassis only pressed steel 6-light saloon Weymann saloon Weymann Sportsman's Coupé[8]
Powertrain
Engine	1,410 cc (86 cu in) ohv st.6 12[8] 1,577 cc (96 cu in) ohv st. 6 14[9]
Dimensions
Wheelbase	104 in (2,641.6 mm) 112 in (2,844.8 mm) Speed track 50 in (1,270.0 mm)[8]
Kerb weight	2,912 lb (1,321 kg)

Spencer Wilks was given almost a free hand to make improvements from the time he began his work at Rover. Intending to cater for the market for then fashionable multi-cylindered engines, big cars might have 16-cylinders, Wilks asked Hillman engine designer B H Thomas to design a new small 6-cylinder engine to fit between Rover's Wild designed 10/25 4-cylinder and Poppe's 2 or 2½-litre 6-cylinder. Thomas's design was effectively a 10/25 engine with two more cylinders though dimensions differed to make it fit within the desired tax rating. It would form the basis for Rover's other engines for the 1930s. In its original version the new engine was described as "nice but quite gutless". It was at first squeezed onto the old scarcely altered Rover 8, 9/20, 10/25 chassis.^[10]

Rover's new car was announced 21 August 1931 described in advertisements as: a 12-horsepower six-cylinder having a four-speed gearbox with a silent third gear, capable of 65 to 70 mph and 28 to 30 miles per gallon^[11] A de luxe model included safety glass in all windows.^[8]

Road test

"The engine exerts its power with an air so modest as to be deceptive" declared Autocar in its report timed to match the release of the Pilot. Gear changing, said Autocar, is easy, it takes carelessness to make any noise. The intermediate gears are "unexpectedly quiet".^[12]

Frame revisions

In February 1932 "following a reorganisation of the company's management"^{[note 1]} Rover announced strengthening of the Pilot and Family Ten chassis by using heavier gauge material and re-designed cross members to improve torsional rigidity. These improvements were, they said, the outcome of lengthy testing on New Zealand's and Australia's roughest roads carried out to make the cars suitable for overseas use. The Pilot scuttle was made wider to give more foot room. The crankcase had been enlarged to provide a larger oil capacity, compression ratio lifted and petrol was now supplied from a new rear tank by Autovac. All Pilot brakes now had a vacuum servo. Springing had also been improved. Safety glass was now standard throughout the Pilot range. There were detail improvements in the de luxe car now trimmed in hide.^[13]

Speed Pilot and Pilot 14

It was announced in July 1932^[9] that the engine's size had been expanded to 1577 cc and 14 fiscal horsepower. Fitted with three carburettors and with a claimed output of 35 horsepower it was sold as Rover's Pilot 14 and in long wheelbase tuned form Speed Pilot.^[9]

Special plant was installed at Rover's works to spray the inside of all body panels with asbestos to ensure quietness fire-proofing etc. and insulation from extremes of heat and cold.^[9]

Also in July 1932 the Pilot received the wholly new chassis of the Ten Special, its flexible engine mountings,^[10] Startix and the new gearbox and freewheel. The new brakes were Lockheed hydraulic with large diameter drums, they were self-compensating and self-lubricating.^[9] The Speed Pilot's special engine had a high efficiency head and a higher compression ratio and a special camshaft. The wheelbase was 8 inches longer.^[14]

Radiator cap mascots

Viking head mascots fitted to Pilots and Speed Pilots had the wings on the helmets swept back almost to the horizontal.^[15]

Underslung frame

But the chassis frame which previously rose over the back axle was now straightened and set to run beneath the back axle. While this limited suspension movement it allowed lower bodywork with a more sporting appearance.^[10]

Road test of Pilot 14

Under test by The Times its correspondent wrote that the 1577 cc car's great charm lay in its quietness at all times, furthermore the engine was silky and the intermediate gears produced no hum. Pick-up was good in view of the size of the engine and the weight of the car. The suspension permitted wheel bounce. The clutch pedal was too close to the steering column.^[16] Twelve months later a subsequent road test reported that fresh modifications allowed the engine a more spontaneous response. Wheel bounce remained a problem.^[17]

Success

The success of Spencer Wilks' Pilot set the style for Rovers until 1949. The New Deal cars came out twelve months later in late summer 1933.^[10]