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 on the relationship between ignition sparking plug voltage and the acceleration performance of a chassis.
| Identifier | ExFiles\Box 162\3\ img001 | |
| Date | 12th June 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Ra. c. to Mx.{John H Maddocks - Chief Proving Officer} Sparking Plugs general 6000 Hs{Lord Ernest Hives - Chair}/Wst.II/JH.12.6.36. Relation of ignition sparking Plugs Voltage to Acceleration performance of chassis. When Mr. Kennington of the Delco Remy Co. visited us last he demonstrated to us on his 14 HP. Vauxhall the measurable difference in sparking plug voltage between "pick-up" conditions and running conditions under load. His theory was that the difference was caused by incorrect mixture in the induction pipe as compared with the balanced effect obtained when the equivalent loaded conditions are produced at constant speed. We immediately instituted tests ourselves on a Bentley experimental chassis G-H-lV to determine whether these effects could be reproduced. The engine was rigged up with K.L.G. 850 sparking plugs set at .020" a lead taken from each plug in turn to a spark gap in the driving seat, the spark gap being inparallel in turn with each plug. The spark was adjusted and the test results are as follows :- The spark gap was opened out until only occasional sparks occured on the "pick-up" at 10, 15, and 20 miles per hour. The speed was then held down by the brake at full throttle to the speeds in question, i.e. 10, 15 and 20 miles per hour and the spark gap readjusted until sparks occured. The difference in the lengths of the sparks as measured on the gap is recorded below :- | ||