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).
Battery ignition sparking plug voltage tests carried out on 20/25 and 40/50 chassis.
| Identifier | ExFiles\Box 37\1\ scan 185 | |
| Date | 5th December 1930 | |
| E7C. X3199 Date 5-12-30 Ref No. WE63 X.NOS 5970, 8970, 5680, 7680, 8712. Battery ignition sparking plug voltage tests on 20/25 and 40/50 chassis We have carried out a series of road tests on the battery ignition system of the 20/25 HP and the 40/50 HP Phantom II chassis in order to ascertain the maximum voltage necessary to operate the sparking plugs under the worst pressure conditions in the cylinder i.e. "pick up" on top gear full throttle ignition lever retarded from about 10 miles to 25 miles per hour. This voltage was measured by using our calibrated sphere gap voltmeter which was shunted across each sparking plug in turn and so adjusted in each case as to spark over when the absolute maximum voltage condition was reached. Several trials were made with each plug in order to get the maximum voltage. This procedure was carried out with Standard Lodge type C plugs. | ||