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).
Inter-office letter discussing engine pre-ignition problems related to induction pipes and spark plugs.
| Identifier | ExFiles\Box 75\2\ scan0236 | |
| Date | 1st August 1921 | |
| R.R.A. 25 25m. 12-20-20 40849 X2758 INTER-OFFICE CORRESPONDENCE ROLLS-ROYCE OF AMERICA, INC SPRINGFIELD, MASS. CC Mr. Belnap Mr. Nadin Oy2 - G 1821 August 1, 1921 Dear Hives: Re: Induction Pipes Replying Hs{Lord Ernest Hives - Chair}/LG 12.7.21: In your recent very interesting letter you try to bludgeon me into insensibility on the subject of pre-ignition in our heated inlet pipe with the jacket at the Tee. I brought this up at a recent meeting of the Engineering Committee and Hulley confirmed the symptoms. The rotation of the engine was sensibly checked suddenly at times, only when driving on battery ignition (pocket position), the porcelains of the plugs were perfectly clean when put in and perfectly clean when taken out, but browned and iridescent, as though badly roasted. The engine stank when the bonnet was opened like a cheap German toy engine on its first run. Finally, Hulley claims that the engine gave a few shots forwards and then a spin backwards when switched off, though I don't remember this at that time, though it did happen on 4-EX I remember, when it was dirty, after we returned from our trip to the west. I think from this it is evident that something, possibly the spark plugs were so darned hot that they fired the charge on the upstroke. They were made hotter than usual, of course, by the hot inlet gas instead of the cool inlet gas which usually keeps them in decent condition. The plugs used on our tests were Champion Toledo A-63, referred to by Nelson as excellent in his high compression tests in February Journal. Finally we scraped off the exhaust valves some yellow crust which Allen analyzed and said was chromium oxide, which could not form except at a very high temperature. I think all this looks similar to your aero engine experiments in pre-ignition, when you found this to be the prime cause of immensely high temperatures which burnt out exhaust valves and was caused itself by a plug porcelain which had passed a certain critical stage of red-heat. You remember this was published broadcast during the war. | ||