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).
Specifications for the first Myth camshaft, including duration, valve lift and overlap.
| Identifier | ExFiles\Box 159\5\ scan0159 | |
| Date | 8th March 1941 | |
| Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} from Rm.{William Robotham - Chief Engineer} c. Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} Instructions to Shop 1373 Rm.{William Robotham - Chief Engineer}9/ML.8.3.41. MYTH CAMSHAFT. Confirming our conversation re the first camshaft for the Myth. We have agreed that the first inlet cam shall have a duration of 190° measured at .030 tappet clearance; the exhaust - 215° at the same tappet clearance. I should like the valve lift to be as high as is compatible with bouncing speed of 4750 r.p.m. We agreed that the toe of the Myth camshaft should be of the same type as that of the Senior Range camshafts. Our recommendations for the Myth are based on the fact that the only Senior Range camshaft which gives sufficiently good idling so far, is inlet EX.33975, and this has an inlet duration of 200° and an exhaust duration of 218° measured at .030 tappet clearance. The first camshaft instructed should have 20° negative overlap at .030 tappet clearance. Rm.{William Robotham - Chief Engineer} | ||