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).
Testing procedures for a magneto, detailing various RPM runs, force limits, and spark gap settings.
| Identifier | ExFiles\Box 43\4\ Scan030 | |
| Date | 13th December 1926 guessed | |
| -2- Contd. (4) The contact breaker cover shall be replaced, and screwed up in position, and a test shall be made of the tangential force at lever pin radius necessary to cause advance or retard. In various positions this shall everywhere lie between the limits 5 lbs. and 8 lbs. (5) The machine, with the control lever in the central position, shall now receive a preliminary run at 2000 r.p.m. for half a minute with the secondary winding short circuited, and following this a second run with the lever advanced for half a minute with the H.T. discharge taking place on the safety spark gap. (6) Now replace the distributor ring and connect up the H.T. terminals to 12 spark gaps in sequence, set at 5.5 mm. The magneto, with the control lever central, shall be run at 2000 r.p.m. for a period of 15 minutes, followed by a run with lever advanced at 3000 r.p.m. for another period of 15 minutes, during both of which times no appreciable missing shall occur on 5.5 mm. gaps in air. The magneto shall now again be run with the lever fully advanced at 3600 r.p.m. for one minute, during which no misfiring shall occur on the 5.5 mm. gaps. (7) The slowest speeds at which regular sparking will occur on 5.5 mm. gaps in air shall now be ascertained and shall not exceed for (a) Fully advanced position 170 r.p.m. (b) Central position 210 r.p.m. (c) Fully retarded position 260 r.p.m. Note:- The minimum sparking speed for each of the three positions can be taken to be that speed at which 72 consecutive sparks, without missing, are given by the magneto at some time within a period not greater than 5 minutes. | ||