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).
The testing and performance of Mercury spark plugs in comparison with Lodge plugs.
| Identifier | ExFiles\Box 50\2\ Scan056 | |
| Date | 11th January 1927 | |
| X 4295 Hs.{Lord Ernest Hives - Chair} from F.P. To: By: Ref: EP{G. Eric Platford - Chief Quality Engineer}12/F10.5.A. F.R. RECEIVED 11.1.27 MERCURY PLUGS. AVW We have now run the above on several cars on test, also on two of our Trials cars. We certainly find the plug is much less inclined to give trouble from sooting up or overoiling than the Lodge plug, and even on engines which are actually condemned for overoiling, we find the plug does not fail but continues to fire satisfactorily until the electrodes themselves are actually bridged across. We have only so far used these plugs for the intermediate position, which are the chief culprits so far as this complaint is concerned. On the contrary, we understand that in the pocket position they are likely to give trouble of missing fire due to the oxidising of the electrodes. We have not experienced this trouble in the intermediate position, which generally is in a damp condition. In view of our present trouble with Lodge plugs and the experience which we have had with the Mercury plugs, we strongly recommend that until something further is developed, the Mercury plugs should be used for the intermediate position and the present Lodge for the pocket position. We certainly find that we are actually able to overcome the trouble of ignition failure on a considerable number of customers' cars by this action. The number of complaints we are having in this respect, which we are experiencing ourselves, and which the Depots are also experiencing, is considerable, and it should be universally pointed out to them that until further notice the action as above suggested should be taken. The alternative to this is that a considerable amount of money is being expended in dismantling and refitting engines in order that the amount of lubrication to the cylinders can be reduced, and such action we are very much against, as we certainly advocate that cylinders should be amply lubricated, otherwise the engine gives trouble in other respects. We have experienced the following failures with these plugs :- 1. Gas blowing past the porcelain. - The packing material in this case appears to have been burnt or broken through. | ||