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 Ethyl Export Corporation discussing valve seat insert materials and fitting methods for engines.
| Identifier | ExFiles\Box 150\1\ scan0125 | |
| Date | 29th June 1936 | |
| Swoll. X1282 ETHYL EXPORT CORPORATION CHRYSLER BUILDING 405 LEXINGTON AVENUE NEW YORK June 29, 1936 Mr. W. A.{Mr Adams} Robotham Experimental Department Rolls Royce Ltd., Nightingale Road Derby, England. Dear Rm{William Robotham - Chief Engineer}: Your letter regarding the pounding of valve seats in the Bentley car has just arrived and I have been speaking to Heron on the matter and he has given me the following information which I repeat verbatim: "Inserts in this country in passenger cars and in the cheaper model trucks are, as a rule, straight sided pressed-in rings, in general very similar in form to those used in American Aircraft engines. The pressing instead of shrinking is, I believe, distinctly inferior and there is some evidence that some engine makers will, in the future, use shrinking rather than pressing. In the less expensive applications a hard cast iron containing 5% molybdenum, 3% chromium, 2% carbon, 1-1/2% silicon, patented by Colwell, is in most general use. All the carbon is in solution as carbide in this analysis, and it might almost be described as a white iron. Colwell is sending me a pamphlet dealing with this material and I will forward it later. In the heavy duty truck and bus jobs, threaded-in inserts faced with Stellite No. 1 or Stellite No. 6 are in very general use and seem to be the most durable combination that can be obtained. In this type the Stellite is applied to Silcrome 1 or Silcrome F, both of these materials having coefficients of expansion which are suitable for use in a cast iron head. Silcrome F scales like the devil in Stelliting and I would recommend strongly nickel plating prior to the application of Stellite. I may say that where the screwed-in insert is used, it is usually not shrunk and a certain amount of trouble has arisen from loosening in service. Some of the makers using threaded inserts are experimenting with the plain shrunk type as a result of the above mentioned loosening." | ||