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 performance of Phantom cylinders with an extended bore, focusing on piston knock and bedding procedures.
| Identifier | ExFiles\Box 65\4\ scan0362 | |
| Date | 12th April 1927 | |
| Hs.{Lord Ernest Hives - Chair} By Wor.{Arthur Wormald - General Works Manager} c Sft.{Mr Swift} from Mx.{John H Maddocks - Chief Proving Officer} /8050 Mx{John H Maddocks - Chief Proving Officer}5/T12.4.27 PHANTOM CYLINDERS WITH APPROX. .5 EXTENSION TO BORE. We have now fitted 4 sets of these to engines on chassis, and in every case they have proved successful. They have all been fitted to engines which were particularly troublesome for piston knocks. They are not a cure all, and it is necessary in conjunction with them, that pistons should be good fitting with good bedding. This of course applies to all pistons, but is not easy to achieve. We do not get from the Grinding Machines, pistons which give us decent bedding, and a certain amount of handwork has to be done on them. With the best of workmanship, this tends to leave us with a piston which is patchy, and needs a lot of running in, before a decent bedding is obtained. We have proved that good bedding of the piston is an essential feature, and have obtained it on several sets of pistons, by rubbing them in to a half cylinder with a mixture of shinio and sulphur. I do not think it is practical to do this as a production job, but the results we achieve by these pistons, show the need for improvement in the initial bedding. Although the lengthened cylinders were instructed at the time of our conference on the subject of Phantom piston knocks, it will be a week or two before we get them on production. It would be a great help to us in dealing with troubles on engines on test, if Sft.{Mr Swift} would push, say 1/2 dozen sets of these cylinders, and pass them on to me. The cylinders that they replace, need not necessarily be scrapped, and may be quite a reasonable proposition on other engines, as although the Phantom knock originates with the piston, there are certain crankcases which appear to amplify the sound more than others. | ||