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).
Recommendation to reduce spark plug gaps for tank engines with screened ignition systems.
| Identifier | ExFiles\Box 163\2\ img007 | |
| Date | 6th August 1932 | |
| -2- engine, was 14200. Allowing for a reduction due to the increased temperature of the electrodes under working conditions of 3000 volts, this gives 11,200 as the working voltage for starting up from cold. It will be seen, therefore, that with the screening it would be impracticable for all conditions of running to use a .020" gap. With a gap of .015" at the plug points, the voltage was reduced for the same pressure conditions to 11,300 which, with a similar reduction of 3000 volts for the rise in temperature of the electrodes, gives 8300 volts which should work fairly well with screened ignition. It will be appreciated that an ignition system so screened will be far less capable of dealing with the carboned plugs or leakages on the high tension system such as are usually met with under service conditions, and it will probably be found that the plugs will require much more attention than is usual with the ordinary 20/25 engine ignition. We recommend, therefore, that the plug gaps on these tank engines be reduced to .015". Hs{Lord Ernest Hives - Chair}/Wst. | ||