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).
Seeking clarification on the specified limits for sparking plug air gaps.
| Identifier | ExFiles\Box 79\1\ scan0085 | |
| Date | 15th January 1917 | |
| To WB.{Mr Brazier/Mr Bell} from BY.{R.W. Bailey - Chief Engineer} Copy to EFC. 15th January, 1917. BY3/G15117. X.601. RE SPARKING PLUGS. Referring once more to the above question and Messrs. Lodge's letter of the 12th January reference BH/HB{C. E. Harcombe}, we are not quite clear with regard to their memo. (1) Do they mean that the limits which they have given refer to one plug only, that is, that on one side of the electrode the gap may be as low as .0125" and therefore on the other side will be as high as .0225" ? (2) or do they mean that separate plugs will have the following limits - (a) The plug with the smallest air gap will be .0125" at the narrowest part. (b) On another plug the smallest air gap will be .0225". If their meaning is described in our paragraph (1) then we are quite satisfied to accept the plugs. If, however, by their limits they mean what we have stated in paragraph (2) it appears to us that the widest limit which they specify for the narrowest part of the air gap is too wide. BY.{R.W. Bailey - Chief Engineer} | ||