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).
Photograph showing two different types of engine valves.
| Identifier | ExFiles\Box 1\8\ B001_X100 Engine Chassis-page227 | |
| Date | 4th October 1932 guessed | |
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