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).
Cylinder bore wear measurements for a 25 EX engine after mileage on Shell oil.
| Identifier | ExFiles\Box 179\2\ img037 | |
| Date | 26th November 1931 | |
| 25 EX ENGINE BORES OF CYLINDERS AFTER 30000 MILES ON Shell Oil [Struck-out text: 34,000 ON SHELL OIL] TABLE DATA: BORE N° | MEASURED AT | DIAMETER | WEAR 1 | CROWN | 4.2522 | .0022 1 | CENTRE | 4.253 | .003 1 | MOUTH | 4.251 | .001 2 | CROWN | 4.2525 | .0025 2 | CENTRE | 4.253 | .003 2 | MOUTH | 4.2512 | .0012 3 | CROWN | 4.2522 | .0022 3 | CENTRE | 4.2527 | .0027 3 | MOUTH | 4.251 | .001 4 | CROWN | 4.2528 | .0028 4 | CENTRE | 4.2532 | .0032 4 | MOUTH | 4.2512 | .0012 5 | CROWN | 4.2522 | .0022 5 | CENTRE | 4.253 | .003 5 | MOUTH | 4.251 | .001 6 | CROWN | 4.2526 | .0026 6 | CENTRE | 4.253 | .003 6 | MOUTH | 4.2512 | .0012 DRAWING SIZE 4.250" DIA | ||