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 lowest speeds in RPM for regular firing of various magnetos (Condor & Hawk size).
| Identifier | ExFiles\Box 4\5\ 05-page248 | |
| Date | 14th September 1923 | |
| x430 4D. 14.9.23. X.430. MAGNETOS. (CONDOR & HAWK SIZE) TABLE OF LOWEST SPEEDS IN R.P.M. FOR REGULAR FIRING ON 5.5 MM. GAPS IN AIR. CHAIN DRIVE. N.B. Test Range between advance and retard 58° in all cases. Magneto. | Type & No. | X. No. | Lowest speeds. | Remarks. | | | Adv. | Cent. | Retd. | -------------------------------------------------------------------------------- ...Bosch | ZF.6. | 4568. | 400 | 450 | 450 | | 2490573 | | | | | | 2490577 | | 380 | 380 | 380 | -------------------------------------------------------------------------------- Scintilla| AMS-A | 4167 | 220 | 320 | 410 | Revolving magnet type | 26485 | | | | | -------------------------------------------------------------------------------- Watford | R.O.1. | 3551 | 220 | 190 | 190 | Original experimental machine. | No.3. | | | | | Cobalt steel magnets. | | | | | | ~~of 58°~~ 34° range used -------------------------------------------------------------------------------- Watford | R.O.1. | 3551 | 160 | 125 | 118 | Later machine | 67642 | | | | | 58° range 14.9.23. | ||