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 the Phantom III camshaft to improve low-speed M.E.P.
| Identifier | ExFiles\Box 93\5\ scan0039 | |
| Date | 19th November 1936 | |
| 307 To E.{Mr Elliott - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}5/AP.19.11.36. PHANTOM III. CAMSHAFT. We are anxious to improve the low speed M.E.P. more or less irrespective of a drop in power at high speeds for the standard Phantom III. Our present camshaft has a duration of 220° on each cam at .020" tappet clearance and we should like to start off by cutting them down to 210°. The valve timing would then be - I.O. 6° P.T.D.C. E.O. 36° B.B.D.C. I.C. 36° P.B.D.C. E.C. 6° B.B.D.C. Leaving the positions of I.O. and E.C. as standard this amount of negative overlap being dictated by the slow running. The Cadillac V.12. has cam durations of 204° and 206° for inlet and exhaust respectively. In view of the efforts to discontinue with auto adjusting tappets, the camshaft to be designed with long toes as per LeC.5319. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} | ||