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).
Specification table for Spectre Double Taper Valve Springs, part numbers Hs.1827 and Hs.1828.
| Identifier | ExFiles\Box 96\2\ scan0034 | |
| Date | 8th March 1935 | |
| Hs{Lord Ernest Hives - Chair}/Smth. 6/KW. 8.3.35. SpectreCodename for Phantom III Double Taper Valve Springs - Hs.{Lord Ernest Hives - Chair}1827/S. | | Hs.{Lord Ernest Hives - Chair}1827 Outer Spring | Hs.{Lord Ernest Hives - Chair}1828 Inner Spring | |---|---|---| | Wire dia. | .192 | .116 | | Mean Coil dia. Top | 1.108 | .722 | | " " " Bottom | 1.508 | 1.032 | | No. of effective coils | 4½ | 5¼ | | Total No. of coils | 6 | 7 | | Rate | 174 | 64 | | Load - Valve closed | 43.8 | 21.2 | | Free length | 1.852 | 1.631 | | Max. stress - corrected | 70,000 | 79,000 | Hs{Lord Ernest Hives - Chair}/Smth. | ||