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).
Ignition faults due to sooty plugs, comparing mica and porcelain types, and recommending better quality petrol.
| Identifier | ExFiles\Box 183\M22\ img050 | |
| Date | 1st November 1919 | |
| To BN.{W.O. Bentley / Mr Barrington} from R.{Sir Henry Royce} -2- R4/G1/11/19 Contd. in the ignition may result in an improvement. The faults I have seen have only been capable of being met by changing the plugs to clean ones, and therefore conclude that the fault is with the plugs, and it may be that these mica plugs are not ones that keep themselves so clean as the porcelain plugs which get very hot and the carbon is burned from the insulating surface during the heavy running. The reason for the sooty plugs appears to be due to excess of petrol used during starting up. It was particularly noticed in our case that the quality of petrol was very doubtful. I therefore think that it will be found that the whole trouble occurs when one gets hold of some bad petrol and soots their plugs; remedy - use porcelain plugs and better petrol. Make the modifications agreed to above, as soon as ever convenient. In the meantime, use every endeavour to be sure that the coils are well insulated between the layers of the winding. My own impression is that our coils are well insulated, if we are using the experience we gained with our old trembler coil. R.{Sir Henry Royce} | ||