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).
Testing split pistons, their clearances, and difficulties diagnosing engine knock using a stroboscopic telephone.
| Identifier | ExFiles\Box 35\2\ scan 155 | |
| Date | 17th October 1919 | |
| R.R. 235a (500 T) (S.D. 408. 28-4-17.) Bm. 2/156/13. Contd. -35- EH5/LG1710.19. started up it is very difficult to pick out any knock, what noise there is from the pistons disappears before the car has stopped popping and spluttering and is running evenly. We have done the worst things we know of to try and seize it up but have not been successful. The clearance we are running with on the fitting portion of these pistons to .006" to .004". With this clearance, of course, we should expect that some of these pistons will knock when cold. We consider this split piston is a hopeful proposition and we should like Mr. Royce to confirm that he agrees with us continuing the tests with these pistons in parallel with other experiments. We have spent some time in conjunction with Mr. Clark to try and get the stroboscopic telephone working properly. So far we have found it very difficult to overcome the noise of the clicking caused by the making and breaking the circuit. We can hear the pistons knocking in the telephone quite distinctly more distinctly than standing close to the engine. EH. | ||