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 piston weights for Spectre and Bentley models.
| Identifier | ExFiles\Box 88\3\ scan0066 | |
| Date | 12th November 1934 | |
| x258 12.11.34. Comparative Weights of Pistons. SpectreCodename for Phantom III. Complete with Rings & Gudgeon Pin. = 20¾ ozs. Without Gudgeon Pin = 16¼ ozs. Bentley. Complete with Rings & Gudgeon Pin = 23¼ ozs. Without Gudgeon Pin = 19 ozs. | ||