This page illustrates some of the more interesting or unusual points of the P4's technical design. The pictures are taken from a 1954 Rover brochure.
Looking at the right-hand side of the engine, the inlet manifold cast in unit with the cylinder head can be seen.
This engine is from a "90", so it has a single SU carburettor. Note the flexible tube connecting the top of the float chamber with the air inlet elbow. This is part of an economy device that lowers the atmospheric pressure on the fuel in the float chamber under conditions of light load and small throttle opening.
The fittings visible on the sump (above and to the left of the drain plug) are the removable oil filter screen and the sender for the electrical oil level gauge. (Pressing a button on the facia causes the fuel gauge to read the oil level in the sump.) The small plate on the upper shoulder of the bell housing gives access to the timing marks on the flywheel.
On the left-hand side of the engine, the black cover beneath the exhaust manifold is removed to adjust the exhaust valve rockers. The large full-flow oil filter, which replaced the Wipac bypass unit of earlier models, takes the following elements: Rover 246262, Purolator MF141, GUD GP504,, Unipart GFE111, Ryco R296P. (This is the same filter element used by 6-cylinder Land Rover engines.)
All P4 engines (apart from that of the "80" model) have an Inlet Over Exhaust (IOE) or "F-head"
valve layout. This arrangement, also employed by Rolls-Royce, allows an improved combustion chamber shape and was a feature of all Rover 6-cylinder engines.
The P4 cars were built on a massive ladder-type box-section chassis. Immensely rigid, this contributes to the Rover's feeling of imperturbable solidity.
The two-piece propeller shaft's centre universal joint bearing is supported by a spring to take its weight off the rubber mounting bushes. The grease fittings on the universal joints and sliding spline are the only points requiring greasing on the car.
The front suspension uses unequal length top and bottom control arms together with radius rods. The swivel pins use ball bearings and are lubricated by heavy oil. Many P4s in Canada have been seen with grease nipples replacing the filler plugs on the oil reservoirs. However, grease must not be used to lubricate the swivel pins!