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).
Gas leakage and pre-ignition tests on various spark plugs.
| Identifier | ExFiles\Box 58\2\ Scan075 | |
| Date | 3rd May 1934 guessed | |
| 3. E&I.827 Table 2. Gas leakage results. | Plug. | Leak in c.c/min. | Remarks. | |---------|--------------------|----------------------------| | A.G.10. | | | | 1. | 0.8 cu.cm./min. | Leak from top of insulator.| | 2. | 0.3 cu.cm./min. | Leak from top of insulator.| | A.G.20. | | | | 1. | 3.3 cu.cm./min. | Leak from top of insulator.| | 2. | 5.6 cu.cm./min. | Leak from top of insulator.| | A.G.30. | | | | 1. | 1.0 cu.cm./min. | Leak from top of insulator.| | 2. | Nil. | Leak from top of insulator.| 5. Preignition tests. Tests were made in a Mercury V single cylinder unit to determine the preignition limit of the Siemens sparking plugs as compared with that of standard aero plugs. The compression ratio was 5 . 3 : 1 and the fuel was D.T.D. Specification No.134. The comparison was made by two methods A.{Mr Adams} and B. Method A.{Mr Adams} The engine was run at full throttle R.P.M. 2000 and fixed mixture strength, B.M.E.P. 134 - 136 lb.per sq.inch. The lowest wind speed in miles per hour at which pre-ignition did not occur was determined. The results are given in Table 3 below. Table 3. Pre-ignition limits (method "A"). | Plug | Lowest wind speed M.P.H. no pre-ignition. | Plug washer temperature. | Rear of Cyl: head temp: | |----------|-------------------------------------------|--------------------------|-------------------------| | A.G.10 | 150 | 260°C. | 180°C. | | A.G.20 | 150 | 270°C. | 190°C. | | A.G.30 | 110 | 290°C. | 195°C. | | Standard | 95 | 290°C. | 210°C. | Method B. The engine was run at 2000 R.P.M. Fixed mixture strength and wind speed 95 - 97 M.P.H. The maximum B.M.E.P. at which pre-ignition did not occur was determined. The results are given in table 4 below. | ||