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 requesting an opinion on the condition of engine valves after using a lubricating additive.
| Identifier | ExFiles\Box 89\5\ scan0095 | |
| Date | 29th March 1940 | |
| COPY AD/GMB. 29th March 1940. W.A. Robotham Esq., Messrs. Rolls Royce Ltd., Derby. Dear Mr. Robotham: My 4 1/4 Bentley is at Kingsbury for decoking and I have withdrawn an inlet and an exhaust valve which have not been touch, i.e. ground or cleaned, during 33,000 miles. We have been watching the effect of ADCOIDS on the valves and I should much appreciate your opinion as to the condition of the seatings and stems. Our point is that ADCOIDS are a Godsend not only in lubricating valves but also in reducing the pitting of the seatings, because the ADCOID material tends to keep the carbon somewhat less hard and brittle than is the case in their absence and of course, the harder the carbon the greater the pitting of the seatings owing to fracture of the skin and the less the efficiency, because the hard carbon does in fact interfere with intimate seating and so efficiency is reduced. Again, if the valves are kept open by hard carbon there is burning, which also damages the skin. These properties of ADCOIDS were of course, never contemplated when we first put them on the market simply as a lubricating material which would minimise the corrosion due to the presence of hydro-bromic acid in connection with the heavy doping with lead-tetra-ethyl. Naturally, we do not want these valves touched with the fingers more than necessary, but by applying a little white blotting paper to the carbon you will find that the lubricant is still actually present. Would you kindly return them at your convenience? Kind regards, Yours sincerely, | ||