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 of three different sets of sparking plugs for the Wraith model.
| Identifier | ExFiles\Box 162\3\ img106 | |
| Date | 16th November 1937 | |
| 6060. To Rm{William Robotham - Chief Engineer}/Wym.{G. Harold Whyman - Experimental Manager} from Rm{William Robotham - Chief Engineer}/W.Brazier. c. Rm{William Robotham - Chief Engineer}/Childs. Rm{William Robotham - Chief Engineer}/W.Brazier.5/MH.{M. Huckerby}16.11.37. WRAITH SPARKING PLUGS. We have tested three sets of sparking plugs in 28.G.VI. A.C.X.428, Champion N.A.8, and F.L.B.30.X. using a Delco distributor and 20000 R.R. turn coil. The three sets gave a satisfactory performance at .030 spark gap. The gaps were then opened out to find a safety factor, allowing for wear at the points. While it was possible to increase the gaps above .040" for ordinary running, occasional misfires were experienced. under extreme conditions such as picking up after running slow. ( 5. M.P.H. top gear). We re-set the plugs to .030" and are now watching their performances during mileage. Rm{William Robotham - Chief Engineer}/W.Brazier. | ||