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).
Technical description of the engine's offset cylinder design and valve gear.
| Identifier | ExFiles\Box 22\4\ Scan090 | |
| Date | 30th March 1927 guessed | |
| contd :- -4- This should result in good filling of the cylinders. OFFSET CYLINDERS. A rather unusual feature in the design of this engine is the 'off set' or 'desaxe' arrangement of the cylinders with respect to the crankshaft which amounts to 10 mm ( see diagram ). This results in the top and bottom dead centre positions being assymetrical with regard to the angular position of the crankshaft, requiring 181º 31' 55" movement for the piston to complete the down stroke and 178º 28' 5" for the upstroke apart from any other effect. The off-setting exerts a slight influence on the valve lift diagram when plotted against a piston displacement base but this is not appreciable. VALVE GEAR. The valves - two per cyl. - are push rod operated and controlled by triple springs. Details of these springs together with rating curves are shewn on a separate print. The max: valve lift is .375" and the same cams are used for both inlet and exhaust valves. The free area past the valves when fully open is 1.61 sq.ins. or 60% greater than the 20 HP. contd :- Diagram Text: CYLS. ARE OFFSET 10 m/m.{Mr Moon / Mr Moore} ROTATION OFFSET 10 m/m.{Mr Moon / Mr Moore} TOP CR.{Mr Cra???ster / Mr Chichester} 1º 56' 33" Bottom CR{Mr Cra???ster / Mr Chichester} 3º 28' 23" | ||