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).
Letter from a customer detailing persistent engine knocking and missing issues with their car.
| Identifier | ExFiles\Box 90\2\ scan0159 | |
| Date | 1st June 1937 | |
| Copy of letter from Professor E.C. Dodds. "Dunster", 72A, Teignmouth Road, N.W. 2. 1st June, 1937. A.F. Sidgreaves, Esq., Messrs. Bentley Motors Ltd., 16, Conduit Street, W.1. Dear Sidgreaves, I do not know whether the following account is of any value to your service or experimental people. As you know I have had a lot of trouble with my car missing and knocking. At one period this was ascribed to the use of Ethyl, and on the advice of your experts I changed to Discol. The car went quite well for a time except that it knocked on occasions round about 2,500 revs. The car was decarbonised a little while ago and went perfectly after that for about 2,000 miles, in fact it was the most comfortable running I have ever had. Quite suddenly it began to knock again, and I sent it back to the Service Station who said that something had gone wrong with the ignition. It came back and it still knocked. They fitted new plugs which bore the label FLB 30X. The car still knocked badly and I got your letter saying it was due to dirty plugs, probably due to leaving the mixture control over to strong. This, if you remember, I was convinced did not occur. I had to go away this week-end, and my man put in a new set of plugs, namely the old Standard 850, cleaned those mentioned above, and put them in the tool kit. I set off for the Birmingham district, and as soon as I got out of the controlled area and put my foot down, the car both knocked and missed, and it was impossible to get over 2,500 revs. I stopped, removed the plugs, and inserted the clean ones and drove off. As the engine was still hot there was no need to use the mixture control. The engine knocked from the start. This I think disposes of the theory that the knocking and missing is due either to Ethyl or to dirty plugs. I am at a loss to understand the engine of my car at all. It knocks only at fairly high speeds, namely 2,500 to 3,000 revs, and does not knock when pulling at low speeds. Another very | ||