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 condition of an 18-GIV engine unit after a 10,000-mile test.
| Identifier | ExFiles\Box 179\2\ img075 | |
| Date | 21th December 1931 | |
| ORIGINAL To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/Fm. c. Sg.{Arthur F. Sidgreaves - MD} c. AOF. c. Dea. B. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/AD21.12.31. X5770 X5840 STRIP OF 18-GIV AFTER 10,000 MILE TEST. ENGINE UNIT. Oil. - This unit has been run on Castrol XL oil. The most noticeable feature was that it was very dirty and had the usual deposit of sludge filling about one third of the crankpins, but in addition, the valves were covered with a thin layer of what appeared to be carbonised oil. The holes in the scraper ring groove were, in one case, almost completely filled up and in every case contained a considerable quantity of carbon. The quantity of carbon on the top of the piston was not excessive. We have not previously seen an engine in such a dirty condition when using XL oil. We have taken the matter up with Mr. Evans of Wakefields and he is letting us have his report in due course. Bearings. - It will be noticed from the attached photographs that white metal has broken away from the main bearings on No.4, 2 and 3. Connecting Rod Bearings - General condition good. A small portion broken away from the top half of No.2 bearing. Crankshaft - General condition very good. Pistons - Apart from the heavily carboned state of the rings, in good condition. Cylinders - The condition of the cylinder bores was exceedingly good. We think that one reason why the wear was so slight was because this car was not run at all in winter, and in our experience it is starting up from cold that causes piston wear. Cylinder Head. - Three of the exhaust valve seats were badly pocketed. These were worse than any we have previously experienced. Nancock reports a noticeable improvement in the state of the head on 18-GIV with the new exhaust valves and free exhaust system. We believe that a lot of our exhaust valve troubles have been due to the high back pressure under which they have previously been working. | ||