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).
Troubleshooting a misfire on a Bentley by reversing coil polarity and sourcing correct spark plugs.
| Identifier | ExFiles\Box 90\2\ scan0133 | |
| Date | 16th September 1936 | |
| Handwritten: WST Hotter running Plugs To Sg.{Arthur F. Sidgreaves - MD} Handwritten: What about set Lodge Plugs? Handwritten: Another set of Dud plugs for Banks Professor Dodds' Bentley - B-34-GA. Handwritten: Set of hot K.L.G plugs to be sent to Dodds Rm{William Robotham - Chief Engineer} With reference to Sg.{Arthur F. Sidgreaves - MD}12/E.14.9.36 and Sg.{Arthur F. Sidgreaves - MD}2/E.15.9.36. Since we dealt with Professor Dodds' Bentley at the Works, we have had similar trouble on one of our own experimental Bentley chassis and cured the misfire by reversing the polarity of the coil. This is done quite easily by reversing the low tension connections to the primary of the ignition coil. These connections are secured by two screws on the top of the coil, and Lillie Hall or Cricklewood could do the job in about 5 minutes. We suggest that Professor Dodds' car should be altered in this respect with a view to ascertaining if any similar improvement can be effected. We regret that we have no A.C. plugs or Champion Sparking Plugs suitable for the Bentley Car available at the moment. The Champions we have received had too small a reach and we are awaiting fresh supplies from this Company. The only set of A.C. Plugs we have received are, at the moment, fitted to one of our experimental cars, and it took us about eight weeks to get these as they are of a special design. We have more A.C. plugs on order and will allocate a set of these for Professor Dodds' car as soon as they arrive. The difficulty with our Bentley car is that the sparking plugs are not made to standard S.M.M.T. dimensions, consequently it is very difficult to obtain sparking plugs direct from other firms than K.L.G. without waiting some considerable time, as they have to be made specially. We have taken up the matter with the Design Department, and they are looking into the question of whether the cylinder head can be altered to take standard sparking plugs. We consider, however, that reversing the polarity is worth trying before we do anything else. Hs{Lord Ernest Hives - Chair}/Wst. | ||