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).
Camshaft comparison power curve graph for a Bentley III engine using Ethyl petrol.
| Identifier | ExFiles\Box 108\2\ scan0205 | |
| Date | 16th January 1939 guessed | |
| CAMSHAFT COMPARISON. BENTLEY III. POWER. S.66 "ETHYL" PETROL COMP. RATIO. 6.6 : 1 B III INDUCTION SYSTEM. R.M. 522 PISTONS (170) ① CAMSHAFT E.B. 3466 (TIMING @ .030 CLCE) I.O. 4 5° AT E.O. 38° BB I.C. 47° AB E.C. 3 5° AT ② CAMSHAFT. E.W. 416 (TIMING @ .025 CLCE) I.O. 6 7° AT E.O. 41 3° BB I.C. 39° AB E.C. 7 8° BT{Capt. J. S. Burt - Engineer} ⓐ OPEN EXHAUST ⓑ SILENCED (B II SYSTEM COMPLETE.) B.H.P. R.P.M B.M.P. 1a, 1b, 2a, 2b | ||