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 comparing their own ignition coil against two American-made coils (De Jon and Marelli) on a 20/25 HP car.
| Identifier | WestWitteringFiles\V\2January1931-April1931\ Scan067 | |
| Date | 17th March 1931 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. to ME. Nor. c. to E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. to By.{R.W. Bailey - Chief Engineer} EFC. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}3/KT.17.3.31. X6058 X6101 X6035 AMERICAN IGNITION COILS. We have carried out some tests to compare our own ignition coil with the De Jon and Marelli coils, both of American origin. The tests were carried out on a standard 20/25 HP car; the procedure being to test each coil with varying sparking plug gaps, starting with .020" gap and increasing by .005" until definite misfiring at full throttle low speeds occurred. As far as possible the temperature of the coils was kept identical in each test. A ballast resistance was not used with either of the American coils as we understand they are designed to be used without one. The results obtained show that the two American made coils give an almost identical performance, but they are both slightly inferior to our own coil. All three coils are free from misfiring with a sparking plug gap of .020". With a gap of .025" they all three give indications of misfiring, the American coil worse than our own; at .030" they all three definitely misfire but our coil definitely not so badly as the American coils. These tests were carried out with new K.L.G. type K.I. sparking plugs. Further tests were carried out using a set of M.C.3.S (Lodge) plugs which had been in use for some considerable time. The results obtained were substantially the same with the exception that our own coil gave a better performance by comparison than when K.L.G. K.I. plugs were used, the difference between our coil and the two American ones was definitely more marked. In all these tests our own distributor, low tension contacts, condenser etc. were used. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} | ||