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).
Showing data for engine performance with both ignitions.
| Identifier | Morton\M20.2\ img004 | |
| Date | 1st April 1924 | |
| R.R. 493A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Expl. No. REF: Hm{Capt. W. Hallam - Head Repairs}/ACL/1.4.24. (5) Both Ignitions. Revs. | Lbs. | MAX. | MIN. | MEAN. 2500 | 132 | --- | 42º | 44.5º 2250 | 141 | --- | 40º | 43.5º 2000 | 144 | 46º | 37º | 41.5º 1750 | 151 | 44º | 36.5 | 39º 1500 | 152 | 44º | 33º | 37.5º 1250 | 151 | 41º | 29º | 35º These curves were taken to show advantage of firing a comparatively pure charge, by relieving back pressure, and reducing amount of residual gases, - but are practically identical to figures obtained with std. manifold. ACL/CF. | ||