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).
Four graphs showing Phantom II valve spring rig performance at different RPMs.
| Identifier | ExFiles\Box 17\6\ Scan328 | |
| Date | 29th November 1934 guessed | |
| FIG. 2 PHANTOM II VALVE SPRING RIG No. 1 INLET VALVE STANDARD CAMSHAFT E 82448 STD. PUSH ROD - SPRING E81550 (a) 1500 RPM (b) 2000 RPM (c) 2900 RPM (d) 3500 RPM CLOSING ACCLN. REVERSAL HEAVY POS.VE OPENING HA 14A 7B 8B 14B | ||