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).
Tests conducted on a Bentley Induction System using a spark gap.
| Identifier | ExFiles\Box 82\4\ scan0338 | |
| Date | 11th June 1936 | |
| To Hs{Lord Ernest Hives - Chair}/Em. Hs{Lord Ernest Hives - Chair}/WB.{Mr Brazier/Mr Bell}19/KW.11.6.36. Tests on Bentley Induction System by means of a Spark Gap. We have carried out tests in conjunction with Wst. to determine if the method employed would enlighten us as to the distribution of the Bentley induction system. An adjustable spark gap was connected to each plug in turn and finally to the coil itself. The car was then driven with a light throttle opening at the speeds as shown in the figures attached. With a snap opening of the throttle, the gap was adjusted for the spark to just jump the points and then measured. The tests were repeated and the gaps set and measured, but the speeds in this instance were taken full load. Readings were taken idling, and slow running under load. It was noticed in the case of the snap opening tests that with a stronger mixture the spark would not jump the gap as set to the weaker mixture. A direct comparison between cylinders is probably not wise, due to slight variations in the plug gaps, difference in carb. settings, etc. Comparisons between snap openings and full load speeds seem useful on each cylinder. On cylinders 1, 4 & 6, the snap opening mixture is recorded as being weaker than full load. Nos. 2, 3 & 5 show little if any difference. Taken from the coil, the voltage is higher on pick up than with a fixed speed full load. On all cylinders there is less voltage required at 10 M.P.H. than the two higher speeds. Hs{Lord Ernest Hives - Chair}/W. Brazier. | ||