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).
Distributor head sparking, condenser capacity, and spark gap tests.
| Identifier | WestWitteringFiles\K\September1923\ Scan40 | |
| Date | 14th September 1923 | |
| R.R. 493 A (40 H) (SL 42 12-7-23). J.H., D.{John DeLooze - Company Secretary} EXPERIMENTAL REPORT. Contd. Expl. No. 4357. REF: EFC1/T14.9.23. With the smaller capacity of condenser, .32 mf., the maximum distributor speed which could be attained without causing missing to take place on 6.5 mm. gaps was 1410 r.p.m., corresponding to 2820 r.p.m. of the engine, or to 57 m.p.h. NOTE:- Normal voltage considered to be 12.4. Reduced voltage 8.5 Normal distributor speed 700 r.p.m. It is intended now to make a test on a car on the road, using this distributor head with mica windows to determine if, in any circumstances of running, sparking over can be observed in the distributor head. There is at present no definite evidence of the occurrence of this phenomenon, and if we cannot produce it under the worst conditions of acceleration under full throttle, it would appear that the limitation of the distributor head to the equivalent of 6.5 mm. gap is not serious. EFC. PB.115 att. * N.B. The spark gaps used on our bench tests consisted of an open row of platinum tipped pairs of adjustable points, each with an adjustable third point. It is well known that different types of gaps do not necessarily give the same relation of sparking voltage to length, and therefore it is possible that with other types of gap a larger spark gap than 6.5 mm. may be obtainable without sparking taking place in the distributor. Hence in using other types of spark gap the equivalent gap to our 6.5 mm. would be more accurately represented by the length of gap which just did not allow sparking to take place in the distributor, rather than exactly the 6.5 mm. EFC. | ||