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).
Engine troubles during testing, covering piston failure, valve gear breakages, and spark plug fouling.
| Identifier | WestWitteringFiles\O\2January1926-March1926\ Scan38 | |
| Date | 28th January 1926 guessed | |
| contd :- -6- having two extra webs to each boss extending nearly to the centre of the crown. Die cast "Electron" pistons, (magnesium) have been tried and gave an improvement in the performance especially acceleration etc. After a total of 6 hrs. running one of the pistons became 'holed' in the crown (6.35 to 1 comp. ratio) and it was observed that the 'bars' round the piston showed signs of spreading. These are the troubles usually met with on the bench, though it was rare for the engines to be run for more than 15 mins. 'all out' at 5000 r.p.m. At 4,500 r.p.m., they have run for longer periods - up to about 2 hrs. During attacks upon records, when the engine speed would be somewhere round about 5000 r.p.m., the chief troubles experienced have been with the valves and valve gear. Spring breakages, finger (valve follower) breakages, and valve troubles. The main, and big end bearings seemed to stand up in a satisfactory manner - the rollers running direct on the crank, and in the connecting rods. Trouble was experienced due to plugs oiling up, when the engine was idling before 'getting away' in a race. Owing to the throttle being nearly closed, the depression in the blower casing (suction side) caused oil to be drawn through the bearings from the blower gear chamber. This, in conjunction with a rich petrol/oil mixture, caused fouling of the plugs, and often means their replacement. The K.L.G. 221s, used have heavy copper central electrodes. contd :- | ||