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).
Letter discussing issues with Model B spark plugs and offering Model C9 plugs as a solution for testing.
| Identifier | ExFiles\Box 79\1\ scan0202 | |
| Date | 22th September 1919 | |
| COPY. X607 22nd September 1919 Your ref: EH1/LG Mr. E.{Mr Elliott - Chief Engineer} W. Hives, C/o Messrs. Rolls-Royce Ltd. Nightingale Road, DERBY. Dear Sir, I am in receipt of your letter of the 18th inst., on the subject of sparking plugs for your car engines. I note that the Model B plugs have given trouble owing to leakage inside. By this I understand the spark is leaking inside, and that you do not mean a gas leakage through the plug. This is, in my opinion, the weakest point in the Model B type of plug. The inside surface of the mica washers keeps comparatively cool, and so that soot is deposited rather reasily on the surface across which the spark leaks. The only cure is to keep the insulation hotter. I have no doubt that quite the best plug for your engines is our Model Z, but this is still not ready for commercial production. By the time it is ready, I have no doubt that we shall have got over your complaint about their not standing much oil. I consider that the best plug that we have to offer you at the present time, is our Model C9, of which I enclose a sample. I am perfectly certain that this plug will give complete satisfaction on your cars. The only doubt about I have, is that if you test these plugs on a continuous full-load break test, you may burn the insulation and the plug will pre-ignite. I am enclosing a sample of this Model C9, and am of course, ready at any time to send you a supply for testing. I may mention that in the first batch of this pattern, the inside joint was made with an aluminium tube, which in previous designs has been P.T.O. | ||