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).
Comparison of engine component specifications for the Spectre and Phantom models.
| Identifier | ExFiles\Box 96\2\ scan0020 | |
| Date | 18th January 1935 | |
| SPECTRECodename for Phantom III CAMSHAFT 1.25 Camshaft Speed - 2250 Rubbing Speed - 88 TAPPET PAD .45 Valve Spring 52 lbs to 125. Tappet spring. 9 lbs to 21.5 lbs. Load on tappet per inch. 115 lbs to 280. PHANTOM. CAMSHAFT 1.1 Cam Speed - 1750 r.p.m. Rubbing Speed - 60 TAPPET PAD .575 Valve Spring 85 lbs to 160. 20 lbs to 52. 148 lbs to 280. | ||