Graph plotting ignition firing position against engine RPM to determine the optimal advance for maximum torque and to avoid detonation.
| Identifier | ExFiles\Box 65\4\ scan0319 | |
| Date | 18th August 1925 | |
| BOTH IGNITIONS IN OPERATION. SINGLE CYL. 5.2 TO 1 COMP. RATIO. ADVANCE REQ. FOR MAX TORQUE ALSO ADV. REQ. FOR NO DETONATION. THE LETTERS ON CURVES INDICATE THE IGNS. TO WHICH THEY REFER. FIRING POSITION DEGREES OF CRANKSHAFT. 40° 30° 20° 10° TOP CENTRE 0° -10 R.P.M. 250 500 750 1000 1250. BEST COMBINATION FOR MAX TORQUE & MIN. DETONATION COMBINATION FOR NO DETONATION. MAX TORQUE CANNOT BE OBTAINED WITHOUT DETONATION A.C.L. 18/8/25 3 | ||
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).