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 Lodge Plugs Limited comparing two models of spark plugs, HC3 and HD3, for Phantom cars.
| Identifier | ExFiles\Box 162\6\ img239 | |
| Date | 15th February 1934 | |
| Telephone, 276 RUGBY (2 lines) Established 1904. Telegrams, "LODGE, RUGBY." Lodge Plugs Limited, Rugby. Messrs. Rolls-Royce Limited, D E R B Y. Your Ref. Our Ref. WS/MSD Date 15 February 1934. DIRECTORS: J.{Mr Johnson W.M.} ALFRED HOPPS. BERNARD HOPPS. ALEC M.{Mr Moon / Mr Moore} LODGE. F.{Mr Friese} BRODIE LODGE. All letters must be addressed to the Company, not to individuals For the attention of Mr. West. Experimental Dept. Dear Sirs, Plugs for Phantom Cars. -------------- Referring to our interview with Mr. West on Monday, the differences between model HC3, which you are at present fitting to the Phantom engine, and the model HD{Mr Hayward/Mr Huddy}3, which you are testing, are as follows:- HC3. HD{Mr Hayward/Mr Huddy}3. Insulation. Mica internally with All mica. steatite external cap. Body hexagon. Standard 9/16" whit. ½" whit. (1.101" across flats). (.919" across flats) Central electrode.Standard .11" diameter. Heavy 5/32" diameter Both plugs have three point earth electrodes and copper cooled centre pins. The internal leakage surface of the insulation and the internal gas clearances are about the same in both plugs. We would remind you that about twelve months ago you approved and decided to adopt for the Phantom car a plug having a ½" whit. hexagon, but later reversed your decision owing, we understood, to objection from your Service Department who considered the heavier 9/16" hexagon should be continued. With regard to a 14 m.m. plug for your future production -1- (Cont'd)... | ||