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).
Table of distributor dimensions with relative and absolute values, noting that segment length figures are an average.
| Identifier | ExFiles\Box 65\3\ scan0021 | |
| Date | 26th May 1927 guessed | |
| -2a- Distributor dimensions. W x Relative. | Absolute(inches) Pitch (P) = 1.000 | 1.260 Make ratio (M) = .690 | .868 Range (R) = .280 | .353 Forward overlap at full advance (Fa) = .126 | .158 Forward overlap at full retard (Fr) = .406 | .511 Backward overlap at full advance (Ba)= .286 | .360 Backward overlap at full retard (Br)= .006 | .007 Width of brush (B) = .143 | .180 > Length of segment (S) = .572 | .730 Distributor dia. (D) = 1.908 | 2.400 . [Handwritten] The length of the segments on this distributor varied considerably the above figures being an average. | ||