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).
Investigating the cause of an engine 'running on after switching off' and the role of spark plugs.
| Identifier | ExFiles\Box 162\3\ img207 | |
| Date | 11th September 1940 | |
| To Rm{William Robotham - Chief Engineer}, from Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation} C. to Rm{William Robotham - Chief Engineer}/sym. Rm{William Robotham - Chief Engineer}/HC. RUNNING ON AFTER SWITCHING OFF". ( Re your memo Rm.{William Robotham - Chief Engineer}12/ML.26.8.40) QUERY. Whether test bed results confirm that ALG.FE30.X plugs were responsible for the trouble, as outlined in Rm{William Robotham - Chief Engineer}/HC.1/SW.22.8.40. ANSWER. No, because we have not used them for test bed work since Ph.III., for which they were standard. We would point out, however, that the above mentioned report does not show that FE.30.X plugs are bad for "running on", since they are stated to be running trouble free in 4.B.30, which balances out the result on 9.B.V. It should be noted that B.30 No.4 is not fitted in 4.B.30 as stated, and in fact has never been on the road. CONCLUSION. We would like to make the following observations generally, concerning this problem of running on. These observations are made from test-bed experience only, and should not be confused with results obtained on the road, which do not necessarily match up. Firstly, the problem is recognised as being due to excessively high combustion chamber temperatures, and the inability to dissipate this heat when the engine is switched off. POSSIBLE CAUSES. 1. Combustion Chamber Wall. ( Inefficient water circulation). 2. Carbon Accumulation. 3. Valves. 4. Spark Plugs. Taking these points in order, we say:- 1. Has been dealt with in our report Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}1/JMS.17.6.40, where we show that improved water circulation has no effect. | ||