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).
Improvements for Car 1 EX, focusing on piston knocking and lubricating oil issues.
| Identifier | ExFiles\Box 35\2\ scan 095 | |
| Date | 21th August 1919 | |
| To EH. from R.{Sir Henry Royce} c. to CJ. c. to BN.{W.O. Bentley / Mr Barrington} c. to DA.{Bernard Day - Chassis Design} c. to Br.{T. E. Bellringer - Repair Manager} c. to EFC! X!2748 R3/G21.8.19. RE CAR 1 EX. X.2565. X.740. X.682. X.2748. Mr. Elliott is preparing a general report on this car dealing with little points which I have noticed should be improved. They are not of sufficient importance to delay output, and many of them can be corrected on test. I am pleased to say that the car was a great success, giving one the impression of a distinct advance on anything we have before produced. The worst point about the running was the knocking of the pistons when the engine was cold. Supposing that the cylinder bores are good, and that we have the minimum clearance that it is possible to run with, it would appear that as all things are compromises, this combination of design of piston and rod and material of piston (aluminium) is the best that we can suggest for this engine. At the same time I believe something might be done as regards lubricating oil, etc. You will remember that 7 CA has much lighter pistons, and does not knock so vigourously as 1 EX. I think, however, it does knock more continuously, not going off so well after running. See attached note (R4/G21.8.19) on lubricating oils. One feels that after a run, and the engine comes in hot, the lubricating oil is very thin and drains away from the pistons, leaving the engine and the cylinder surfaces particularly dry. Now while the engine is running slowly, assuming the Contd. | ||