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).
Investigation into misfires on a 25.G.VI model, tracing the fault to a worn distributor bush.
| Identifier | ExFiles\Box 168\3\ img225 | |
| Date | 17th July 1939 | |
| 6017 / 6119 COPY FOR FILES. To Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/RC.{R. Childs} Typed 17.7.39. RE FAULTY IGNITION ON 25.G.VI. Owing to a report of misfires on "pick-up" on the above car, an investigation has been carried out on the road in co-operation with Rm{William Robotham - Chief Engineer}/WB.{Mr Brazier/Mr Bell} and Rm{William Robotham - Chief Engineer}/EWC. This misfiring was produced on pick-up after a few minutes on the road. As the ignition coil was suspected, we changed over the spare coil with similar results. Both these coils were std. Wraith type. We next tried a Lucas Sports coil which has proved its ability to stand up to hot conditions. No improvement was effected. We then replaced the experimental Lucas vacumatic type distributor with a similar unit made by Delco-Remy. This definitely cured the trouble. On examination we found that a worn Phosphor Bronze Bush allowed the contact plate assembly to move radially .008" to .010", and as this plate is rotated, relative to the governor shaft, through 6 degrees on extreme load conditions by the vacumatic control, the net result would be a poor break with a consequent low secondary voltage, which, under extreme engine conditions would not be sufficient to fire the sparking plug. Rm{William Robotham - Chief Engineer}/RC.{R. Childs} | ||