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).
Power curve graph comparing two different camshafts for a Bentley III engine.
| Identifier | ExFiles\Box 108\2\ scan0203 | |
| Date | 16th January 1939 guessed | |
| CAMSHAFT COMPARISON BENTLEY III POWER "ETHYL" PETROL S 64 COMP. RATIO 6.6:1 B III INDN. SYSTEM RM{William Robotham - Chief Engineer} 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 EXS. 759 (TIMING @ .030 CLCE) I.O. 5.5° AT E.O. 37° BB I.C. 50° AB E.C. 4.5° AT ⓐ OPEN EXHAUST ⓑ SILENCED (B III SYSTEM COMPLETE) B.H.P. M.E.P. R.P.M. 1a, 2a, 1b, 2b | ||