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).
Graph showing ignition governor curves for a 25/30 deturbulated head.
| Identifier | ExFiles\Box 101\2\ scan0028 | |
| Date | 16th May 1932 | |
| S.P. 26. 25/30 IGNITION GOVERNOR CURVES. DETURBULATED HEAD. TEST CARRIED OUT WITH SHELL NO:1. AND STANDARD CHASSIS EXHAUST SILENCER. E.60660 HEAD DETURBULATED TO LEC 5002 (5.86:1 COMP: RATIO) STD: VALVES 1.4 DIA: INLET 1.225 DIA: EXHAUST STD: STROMBERG IND'N SYSTEM. ① ------ IDEAL LINE (MINIMUM ADVANCE FOR MAX: POWER.) ② ----- → LINE TO CUT OUT DETONATIONS. ③ -x- → 2% POWER DROP BY RETARDING. ④ -o-o- → PROPOSED LINE AS GIVEN BY AUTOMATIC OF SPECIALLY PREPARED GOVERNOR. SPARK POSITION FLYWHEEL ° B.T.D.C. ENGINE R.P.M. | ||