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 the performance and design improvements of a sample C9 spark plug.
| Identifier | ExFiles\Box 79\1\ scan0198 | |
| Date | 10th October 1919 guessed | |
| THE LODGE SPARKING PLUG CO. LTD. RUGBY - 2 - plug will give complete satisfaction on your cars. The only doubt about it 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 quite satisfactory, but curiously enough in this pattern gave trouble through the difference in expansion between aluminium and steel. We have now remedied this, and the plugs we are now making I consider to be a really satisfactory design. Yours faithfully, Alex M Lodge AML/MAW | ||