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).
Tabulated list comparing valve opening specifications for various engines.
| Identifier | ExFiles\Box 102\5\ scan0141 | |
| Date | 10th October 1932 guessed | |
| X5095 x 7770 x 5770 x 7090 x 5095 x 3991 x 400. TABULATED LIST OF VALVE OPENINGS. Engine. | Dia. of inlet valve | Lift of inlet valve. | Ratio Lift valve dia. | Valve area per litre dis. ---|---|---|---|--- F.{Mr Friese} engine | 1.625 | .550 | .337 | 2.20 R.{Sir Henry Royce} engine | 1.950 | .570 | .292 | 1.84 25 HP. .050 increased lift China. | 1.35 | .394 | .292 | 2.22 25 HP. Standard China. | 1.35 | .344 | .255 | 2.22 40/50 New Camshaft LeC. 2918 | 1.9 | .470 | .246 | 2.106 40/50 Std. camshaft | 1.9 | .430 | .226 | 2.106 ⬆️ Peregrine | 1.200 | .334 | .279 | 2.69 J.I. | 1.40 | .400 | .285 | 2.37 8 litre Bentley | 1.38 | .335 | .242 | 2.00 | ||