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).
Extract discussing engine over-oiling complaints from the U.S.A. and the performance of 4-ring versus 6-ring pistons.
| Identifier | ExFiles\Box 148\3\ scan0011 | |
| Date | 8th June 1921 | |
| X2748 Extract from R10/G8.6.21. X.3614 - U.S.A. COMPLAINTS. X.2809 X.3754 X.2748 ENGINE OVER-OILING. It was understood that you were long ago going to adopt the 6-ring piston. This will reduce to a marked extent the tendency for over-oiling. We have no objections to your increasing the size of the holes in the groove in connection with the scraper ring. Undoubtedly bad distribution might increase the tendency for over-oiling, due to miss-fire. The complaint may arise due to the practice of running the engine unnecessarily without a load. Over-oiling is an unusual fault with us, and must be due to miss-firing from some cause, such as sooty plugs from bad gasoline, if so, when we can successfully use low grade fuel overoiling should cease. PISTONS. As regards the tightness of the pistons, the 6-ring piston was standardised long time ago, and is undoubtedly superior to the 4-ring, but the 4-ring piston should not be unsatisfactory, as this piston is tighter, more gas-tight than the general run of pistons. Mr. Hives had the impression that you had changed to 6 ring pistons. Nothing in the nature of an alteration to the pistons from aluminium to cast iron can affect either the starting of the engine or the distribution of the petrol. In one case the pistons would not be hot, and in the other | ||