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).
Graph of ignition timing characteristics for a 4 1/2 Litre Bentley engine in both standard and O.H.C. converted forms.
| Identifier | ExFiles\Box 113\5\ scan0216 | |
| Date | 17th October 1936 | |
| IGNITION. 4 1/2 LITRE BENTLEY O.H.C. S.B UNIT N° B.23. (CONVERTED UNIT) ① STD. 4 1/4 LITRE ENGINE (6·5:1 C/R.{Sir Henry Royce}) a IDEAL LINE (MIN. ADV. FOR MAX POWER) b LINE TO CUT OUT DETONATION. } SHELL N° 1 PETROL. ② O.H.C. CONVERSION (6·0:1 C/R) (SPEC: R.H.C/W.S.C.I/LS 17.10.36) a IDEAL LINE (MIN. ADV. FOR MAX. POWER) } SHELL N° 1 PETROL b LINE TO CUT OUT DETONATION. c LINE TO CUT OUT DETONATION. ) SHELL N° 3 PETROL. CRANKSHAFT DEGREES B.T.D.C. R.P.M. C.T.S | ||