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 tungsten ignition contact points, focusing on a three-flat cam modification and a new scrubber design.
| Identifier | ExFiles\Box 35\6\ scan 337 | |
| Date | 18th October 1927 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} Wor.{Arthur Wormald - General Works Manager} c. Ev.{Ivan Evernden - coachwork} X2894 EFC3/T18.10.27. TUNGSTEN IGNITION CONTACT POINTS. X2894 Reference of last report EFC1/T27.9.27. X8892 Four further sample sets of points are now being sent for R's inspection. No. 25. The experimental modification in the case of this set of points is the three-flat cam, allowing only three contacts per revolution instead of six, as with the six-flat, or six-lobe cam. The idea is that the contacts have more time to cool between the breaks. This pair of points was actually run what is in cam revolutions the equivalent of 20,000 miles, but in the number of breaks is only the equivalent of 10,000 miles, this being considered the right way to compare these results with others. It will be noted that the result is not specially good. The bedding was supposed to be initially all across, but for some reason or other the all-across bedding was not apparently maintained. It would appear that had the bedding been maintained the result may have been a good deal better and shown more advantage resulting from the particular experimental modification experimented upon. No misfiring involving trimming during the test occurred. No. 32. New scrubber to LeC.2422 run with mushroom rotor. (Initial bedding all across) The result is no better than might be expected from the use of the undamped scrubber (LeC.2422) and therefore does not appear to show any particular advantage, in the direction of contacts, with the mushroom rotor. It has occurred to us that the mushroom rotor might be still further improved by providing it with vanes and so make it into an air impeller, not so much from the point of view of the operation of the points as in keeping the inside of the distributor free from corrosion. It could not be worse for the points themselves, and might be considerably better. We have noted that we get a much cleaner internal condition of the distributor head when we run with the distribut. removed, so that no jump sparks are taking place inside the distributor head. No misfiring involving trimming during the test occurred. Contd | ||