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).
Scheme drawing comparing valve seatings for 20HP and 40/50 models.
| Identifier | ExFiles\Box 48\4\ Scan110 | |
| Date | 1st December 1919 | |
| SCHEME No 494 15° 45° 20 HP VALVE SEATINGS 30° 45° 40/50 SCALE 10% SCHEME NO 494 ROLLS-ROYCE LTD. NIGHTINGALE RD 1-DEC-19 DERBY | ||