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).
Recommendations for tappet clearances and sparking plugs for the Large Bore 20/25 HP engine.
| Identifier | ExFiles\Box 106\5\ scan0162 | |
| Date | 1st May 1936 | |
| To By.{R.W. Bailey - Chief Engineer} c. to E.{Mr Elliott - Chief Engineer} c. to Mx.{John H Maddocks - Chief Proving Officer} X 534 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}20/KW.1.5.36. Large Bore 20/25 HP. Tappet Clearance. We recommend that the 20/25 tappets should be set at .004" inlet and .006" exhaust. If there is any difficulty on production in getting quiet valve gear with these tappet clearances, we should like to have particulars. With regard to the sparking plugs, the plugs we recommend to enable production to carry on are KLG.831.LR.{Mr Ellor} It must be appreciated that these are plugs which have given trouble due to breakdown of the mica insulation in service, but they are the only ones that give passable slow running. We hope in the immediate future to have a plug which combines the necessary life with the correct slow running characteristics. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||