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).
Contact breaker timing data for a Watford IS.12 Magneto, No. 83133.
| Identifier | ExFiles\Box 43\4\ Scan062 | |
| Date | 9th February 1927 | |
| V4021 9.2.27. CONTACT BREAKER TIMING OF WATFORD IS.12 MAGNETO. NO.83133. Advance. Retard. Make. -6° 9° Break. 46° 61° Make. 86° 101° Break. 138° 153° Advance. Retard. Make. -18° 20° Break. 94° 124° Average in electrical degrees. Range = 15° Make ratio = .578. ----- | ||