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).
Piston knocks in F.2-B series engines, attributing the cause to temporary piston seizure from lack of lubrication on cold starts.
| Identifier | ExFiles\Box 15\3\ Scan030 | |
| Date | 30th April 1929 | |
| R.{Sir Henry Royce} Hs.{Lord Ernest Hives - Chair} BP. EY. Lbc. X7040 Hm{Capt. W. Hallam - Head Repairs}/10/MW30.4.29. CYLINDERS & PISTONS F.2-B SERIES & ONWARDS. We are receiving a serious No.of comparatively new cars with complaints of piston knocks which our examination shows is due to temporary piston seizure. We have formed the opinion that this seizure takes place due to lack of lubrication when the engine is started up from cold. This lack of lubrication does not remain constant, as when the engine is warmed up and used for any length of time and run lightly, oil forms on the plugs, and in some cases a large amount of carbon has formed in the plug itself. In spite of this with the examples we have already dealt with, we cannot say the piston rings and cylinder walls are overlubricated. We should be afraid of cutting down the lubrication. Our experience leads us to think that two things are required: 1. A definite auxiliary oil supply for the first few minutes when the engine is started up from cold. 2. A sparking plug which is capable of withstanding better the oil which accumulates in the present position. possibly a plug which will work as well but is capable of run- ning under hotter conditions in order to burn off the oil. We tried as an experiment longer reach K.L.G. plugs where the points stand out of the pocket 1/2": These were no improvement. Hm.{Capt. W. Hallam - Head Repairs} | ||