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).
Unreliability of sparking plugs and test methods to observe failure modes in 'Eagle' cylinders.
| Identifier | ExFiles\Box 34\2\ Scan095 | |
| Date | 8th 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} EHS/LG.8.5.18. 8th May 1918. X.2514 - SPARKING PLUGS We are continually having new type plugs submitted to us for test. We are always ready to test any new type of plug because it is a part which we are always having trouble with. One can safely say that sparking plugs are the most unreliable part on an engine. With the object of obtaining more information on sparking plugs and also to be able to demonstrate to sparking plug specialists how their plugs fail, we have arranged sparking plug positions in some "Eagle" cylinders under the inlet valve. With the sparking plugs in this position, we can look in the cylinder through the exhaust port when the exhaust valve is working, and actually see the condition of the sparking plug; it is possible to distinguish which part gets hottest. One can also judge how efficiently the heat is got away by switching off the cylinder which is being observed and noted how long it takes for the plug to cool down to the normal temperature. On one of the test rigs we have three cylinders fitted with plugs, we cab observe; each cylinder is fitted with a piston to give a different compression. It is interesting to see the effect with the various compressions. Contd. | ||