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).
The failure of plug leads, diagnosing the causes of insulation breakdown.
| Identifier | ExFiles\Box 101\2\ scan0011 | |
| Date | 26th June 1936 | |
| X500a HOTEL DE FRANCE. CHATEAUROUX. Indre. France. GWH{George W. Hancock - Head Chateauroux}/IMW{Ivan M. Waller - Head of Chateauroux}/4/JAB.26th June 1936 To. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} 22. G.{Mr Griffiths - Chief Accountant / Mr Gnapp} V.{VIENNA} Failure of Plug Leads. The insulation of the plug leads has broken down, and the wires spark direct on to the valve rocker cover, and inside both the metal tubes through which they are led. There was also direct sparking from the main H.T. lead to the plug wires above the distributor. We attribute this to the following :- 1) Effect of under bonnet heat alone deteriorating rubber insulation. 2) Further effect of oil and parrafin on rubber. 3) Increased strain on insulation with use of wide plug gaps, and new distributor and coil. We do not think that causes 1 & 2 would have produced misfiring if the wires had not been enclosed in metal tubes and brought out close to the hot valve cover. In fact we have overcome the trouble temporarily by using the same wires bound together with tape and discarding the tubes. Cause 3 is borne out by the fact that a continual blue discharge is visible down the plug insulators at night. --------- GWH{George W. Hancock - Head Chateauroux}/IMW.{Ivan M. Waller - Head of Chateauroux} I.m.waller. | ||