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).
Timing and design of the Spectre Camshaft.
| Identifier | ExFiles\Box 93\5\ scan0002 | |
| Date | 11th June 1934 | |
| To E.{Mr Elliott - Chief Engineer} +4647 307 Hs{Lord Ernest Hives - Chair}/Smth.18/KW.11.6.34. SpectreCodename for Phantom III Camshaft. On examination of our experience with Bentley and 20/25, we consider that in order to ensure good slow running, the overlap on the SpectreCodename for Phantom III camshaft as given on LeC.3855/6 should be reduced from 4º to 2º with .020" clearance. This should be done by making the exhaust cams to the same form as the inlet and adopting the following timing - Timing with .020 clearance. Angle between the cams = 114º. [Diagram Data] TDC INLET 230º EXHAUST 230º Overlap: 2º Inlet closes: 48º ABDC Exhaust opens: 50º BBDC In this manner we hope to get the best results using the cam forms available, but are of the opinion that the inlet cam duration is too long and should be redesigned to be similar to the 20/25. Hs{Lord Ernest Hives - Chair}/Smth. | ||