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).
Modifications to a cylinder head, including valve guide bosses, valve shapes, and new pistons to increase the compression ratio.
| Identifier | ExFiles\Box 97\3\ scan0207 | |
| Date | 22th July 1939 | |
| -2- Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}2/MH.{M. Huckerby}22.7.39. Cylinder head - Cont'd.{John DeLooze - Company Secretary} (d) Valve guide bosses. The inlet bosses were removed in the modified B.II head, but it may prove to be a good point to retain them on this larger inlet port, for reasons of support. They do not offer the same restriction as did the B.II. (e) Valves. The existing size of valves should be retained, but the inlet valve should be modified in shape to the tulip type. Further to this, the shape could probably be further improved, as the tulip shape is worth about 3% over the "Corniche" type of inlet valve. It is suggested that a special shape of valve should be tried to prove the point, carrying the "tulip" shape more to the extreme, and if anything was gained then a larger valve might be tried with advantage. It is highly probable that herein lies the reason for the lack of power gain, when in the past we have fitted a larger inlet valve. Finally, we are preparing some strengthened Aerolite pistons incorporating the raised crown, these will raise the compression ratio to 10 : 1 where normally with the flat piston the ratio will be 8.7 : 1. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} | ||