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).
Magneto ignition timing, range of advance, and detonation issues.
| Identifier | WestWitteringFiles\U\January1930-April1930\ Scan085 | |
| Date | 6th February 1930 | |
| -2- MAGNETO IGNITION. The range of advance given by the magneto is limited to 36°; all obtained by hand on the control quadrant. As the automatic governor does not control the magneto ignition advance, detonations are very pronounced; a comparatively early timing is necessary for high speed power and this is too early to avoid detonations at low speeds. As the magneto is used only as a spare ignition in case the battery ignition should fail, we do not think we are justified in going to elaborate lengths to avoid detonations. (The only solution is to apply an automatic advance). We should recommend in the case of the 5.25:1 engine, that we retain the present range of control (36°) but retard the timing 5° on the flywheel (viz. retard timing 5° P.T.D.C.) Using this timing, power is lost at high speeds (2 to 3 m.p.h. off the maximum speed) but we cannot advance it further owing to detonations at low speeds. Hs{Lord Ernest Hives - Chair}/AJL. | ||