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).
Recommending an optimal ignition timing of 12 degrees before top dead centre to reduce detonation.
| Identifier | ExFiles\Box 65\1\ scan0227 | |
| Date | 15th July 1929 | |
| To By.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/ACL. C. to E.{Mr Elliott - Chief Engineer} Mx.{John H Maddocks - Chief Proving Officer} C. to EP{G. Eric Platford - Chief Quality Engineer} XY680. HS{Lord Ernest Hives - Chair}/ACL2/MJ.15.7.29. XY680. XY440 S.S. IGNITION TIMING. As the result of tests carried out, we find the most suitable ignition timing for the above engine to be 12° before top dead centre with the ignition control in the full advance position. Both magneto and battery should be set at this. This timing is slightly later than that giving maximum power but the reduction in power of within 2% is justified by the reduction in detonation under road conditions. We therefore recommend that the flywheels are [text crossed out] marked to the 12° timing. Appended are power curves shewing the effect of ignition timing. HS{Lord Ernest Hives - Chair}/ACL. | ||