From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Design specification for an eight-cylinder engine's cylinder head and valve gear.
| Identifier | ExFiles\Box 123\5\ scan0246 | |
| Date | 2nd January 1939 | |
| BY.{R.W. Bailey - Chief Engineer}/NS.{Norman Scott} c. Rm.{William Robotham - Chief Engineer} DA.{Bernard Day - Chassis Design}P/C.2.1.39. -1044 Sudl C.I. CONVENTIONAL 8 - CYLINDER HEAD AND VALVE GEAR. Please receive herewith :- E.CD.1122 Cylinder Head with Conventional Valve Gear - C.I. Conventional 8. The design of this cylinder head and valve gear is substantially the same as for the Wraith 111, increased in length and made suitable for the eight cylinder engine. The central exhaust ports are separated instead of siamesed to allow room for the distributor drive. The combustion chamber is the same as for Wraith 111 and the compression ratio is governed by the type of piston used. We have increased the space between valves on each cylinder by .050" by moving the exhaust valve outward from cylinder centre line. This will allow the inlet valve diameter to be increased to 1.600" if desired, and still retain the same amount of metal between the valve seats as on the standard Wraith 111 heads. Valve rockers with the Vandervel type of bearing bush may be used if required, the rockers being exactly as Wraith 111, the lengths of distance pieces and pedestal bosses are altered slightly to suit the revised spacing of the exhaust valves. All the water holes in the floor of the cylinder head are drilled .250" diameter. The gasket is .030" thick Klingerite and additional holes for the water are shown in this, so that the gasket will not be assembled incorrectly. It should be observed that the maximum diameter of push rod that can be used in this engine is .3125", owing to the restriction created by the push rod holes passing the exhaust ports in the cylinder head, the push rods shown being similar except for length to those used on the Wraith 111 and Bentley 111 engines. .125" The sparking plugs have been raised bodily/as compared with the Wraith 111 plug positions, to improve the coring and also the cooling of the plugs. | ||