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 1\10\ B001_X106 TO X 110-page037 | |
| Date | 12th July 1932 guessed | |
| TABULATED LIST OF VALVE OPENINGS Handwritten notes: X4027, x7770, x5770, x7090, x5090, x3991, x4003, X107 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 | 1.350 | .570 | .232 | 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 | .235 | 2.37 8 litre Bentley | 1.38 | .335 | .242 | 2.00 | ||