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).
Test report on spark plug insulation resistance and sparking characteristics after heating and cooling, followed by engine tests.
| Identifier | ExFiles\Box 35\4\ scan 007 | |
| Date | 17th March 1928 guessed | |
| K.S.341. 5. Table II. Effective Insulation Resistance after Heating and cooling. Plug No. | Effective Resistance by Magneto Ohms. | Insulation Resistance by 1000 Volt Megger. | Sparking Characteristics Under air Pressure after Cooling. ---|---|---|--- | Hot | After cooling | After Cooling | 1 | 1.4 Megs at 200°C | >2 Megs. | Between 100 Megs and Infinity. | Sparking satisfactory up to 75 lb/sq.in. intermittent between 75 and 100 lb/sq.in. Sparking over insulator above 100 lb/sq.in. 2 | 1.14 Megs at 300°C | >2 Megs. | Infinity. | Sparking satisfactory up to 125 lb.sq.in. 3 | 1.3 Megs. at 300°C. | >2 Megs. | Infinity. | Sparking satisfactory up to 200 lb/sq" 4 | > 2 Megs. at 190°C | >2 Megs. | Infinity. | do. 85 lb/sq.in. 5 | > 2 Megs at 200°C | >2 Megs. | Infinity. | do. 185 lb/sq.in 6 | > 2 Megs at 300°C | >2 Megs. | Infinity. | do. 115 lb/sq.in B. Engine Tests after Electrical Tests. On the conclusion of the electrical tests two of the plugs Nos. 2 and 4 which, as originally received, were defective but had been rendered apparently serviceable by the application of a temperature cycle, were tested in the R.A.E.24T single cylinder air cooled unit. The fuel used was standard (20% benzol). Both plugs functioned perfectly satisfactorily, the engine giving about 110 B.M.E.P. at 50 B.H.P. and 1,900 R.P.M. Examination after the test showed that the portion of the porcelain insulator exposed to the hot gases was now perfectly clean and free from deposit of any kind. 7. | ||