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 from AC-Sphinx Sparking Plug Co. Ltd. concerning sample experimental sparking plugs for Bentley.
| Identifier | ExFiles\Box 163\5\ img052 | |
| Date | 1st September 1936 | |
| TELEGRAMS: SPHINX, DUNSTABLE TELEPHONE: DUNSTABLE 360 PRIVATE BRANCH EXCHANGE. THE AC-SPHINX SPARKING PLUG Co. Ltd. DIRECTORS: N. F.{Mr Friese} STOCKBRIDGE, W. O.{Mr Oldham} KENNINGTON, C. J.{Mr Johnson W.M.} BARTLETT. DUNSTABLE BEDFORDSHIRE OUR REF. NFS/GKB. YOUR REF. 1st September, 1936. Messrs. Rolls-Royce Limited, Derby. For the Attention of Mr. H.{Arthur M. Hanbury - Head Complaints} E.{Mr Elliott - Chief Engineer} West. ------------------------------------------ Dear Mr. West, Sample Sparking Plugs for Bentley. We have now prepared for you, as promised, two sets with one spare (i.e., thirteen plugs) as above. These are our experimental type X399 and the thirteen plugs are being sent to you under separate cover today. I should like you to try out these plugs and let us have your report. You will doubtless recollect that you insisted that the plain portion of the plug body beneath the hexagon was to be not less than 11/16". This has unfortunately pushed us into a detachable type of plug for the job - a circumstance which I rather regret, because we here are convinced that a one-piece plug provides us with better heat flow characteristics and should enable us to build a plug having a wider operational range than is possible with a detachable plug. I should like you to have regard to this point when judging your results. Another point I want to mention is that in my opinion the nose of the insulator is unduly long in these samples, and we have made it so to take care of the circumstance, mentioned in your correspondence, that some of your customers "potter about without doing any high speed work". The long insulator nose should take care of this circumstance quite well, but, as you will appreciate, at the other end of the range on high speed work, a long nose may conceivably run you into a slight trace of pre-ignition. Actually, I think that the wonderful heat conductivity of the new material will obviate the latter possibility, and I shall be particularly interested to see from your report whether this is so. Yours faithfully, N.F. STOCKBRIDGE, Managing Director. MAKERS OF AC SPARKING PLUGS - AC AIR CLEANERS - AC PETROL PUMPS - AC PETROL GAUGES - AC OIL FILTERS - AC OIL GAUGES | ||