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).
Various engine bench tests attempting to reproduce and understand the failure of exhaust valves on a 20 HP chassis.
| Identifier | ExFiles\Box 48\4\ Scan184 | |
| Date | 27th December 1922 | |
| x4238 To R. {Sir Henry Royce} from Hs. {Lord Ernest Hives - Chair} c. to CJ. c. to H. {Arthur M. Hanbury - Head Complaints} c. to Da. {Bernard Day - Chassis Design} c. to BY. {R.W. Bailey - Chief Engineer} Hel/LG27.12.22. EXHAUST VALVES FOR 20 HP. CHASSIS. x4238 We carried out a number of tests on the engine bench test in order to reproduce the failure of the exhaust valves. We ran a series of tests with the exhaust valve tappets adjusted so that the valve could not seat. We tried with various clearances between the valve and the seat. We find that if we have above .010" to .015" we get to a stage where, owing to loss of compression, there is very little power. We ran a number of 6-hour tests full power at various speeds under worse conditions. At the finish of these runs the head was removed and the valve examined. We found on each occasion that there was a slight scale formed on the valve seats but there was no sign of burning and with a rub of grinding paste the seating came up perfectly. We repeated the test with the water boiling the whole time. We still could not injure the exhaust valve. During our tests on cylinder heads we ran frequently until practically all the water disappeared and although the valves showed signs of being overheated, we never, during these tests, had an exhaust valve burn. We ran further test with an exhaust valve on which we had filed the seating locally but we still could not injure the valve. We have tried running with plugs which pre-ignite but with this, so far, we have not been able to burn the valve. contd. | ||