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).
Experiments into pre-ignition and ignition, focusing on the overheating effects of different spark plug designs.
| Identifier | ExFiles\Box 34\2\ Scan102 | |
| Date | 15th May 1918 | |
| To R.{Sir Henry Royce} from EH. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to BY.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Da.{Bernard Day - Chassis Design} X2574 EH1/LC15.5.18. X.2410 X.2514. PRE-IGNITIONS & IGNITION In our report on exhaust valves burning, we mentioned that we could not reproduce a pre-ignition which would cause excessive over-heating by arranging a spark to pre-ignite the charge. During our experiments on sparking plugs we went over this again to find out why. The tests on plugs shewed, that although we could make nearly all plugs pre-ignite, there was a big difference in them inasmuch as some of the plugs caused excessive over-heating and others although they pre-ignite do not cause over-heating. We found that the plugs which cause over-heating have a big mass of metal which is red hot. We think that the reason that this type of plug causes over-heating pre-ignitions is that the heating effect of a comparatively large mass of red hot metal warms up a portion of the charge so that it burns more rapidly. On the other hand, the plugs which only have a small centre point which is red hot, cause the charge to burn very slowly. This is confirmed by the results we get when pre-igniting with a spark. We found we can fire the charge with the ignition set 115° before the top of the stroke. The charge does actually fire, if we have it earlier than 115° we get bad miss-fires. The only reason we can see why this very early Contd. R.R. 235A (500 T) (S.D. 408. 28-11-17) | ||