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, relative pitches, and actual measurements for a Lucas ER6 Magneto No. 54b.
| Identifier | ExFiles\Box 40\2\ Scan154 | |
| Date | 28th October 1926 | |
| X8793 28.10.26. LUCAS ER6 MAGNETO No.54b. Distributor dimension. Relative to pitch. Actual measurement. Pitch (P) 1.00 1.318 inches Make ratio (M) .58 .769" Range. (R) .33 .437" Forward overlap at full advance (Fa) .13 .165" Average backward overlap at full retard. (b) .04 .050" Forward overlap at full retard. (Fr) .41 .547" Backward overlap at full advance (Ba) .20 .269" Backward overlap at full retard. (Br) -.13 -.168" Insulation distance. (I) .38 .500" Brush. (B) .15 ..195" Segment. (S) .60 .80" EFC. | ||