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 Lycoming Manufacturing Company discussing the design and materials for exhaust valve guides, specifically concerning counter boring and cooling.
Identifier | ExFiles\Box 174\2\ img308 | |
Date | 10th January 1939 | |
LYCOMING MANUFACTURING COMPANY WILLIAMSPORT, PA.{Mr Paterson} Handwritten: Inv c/o Swol c/o TS c/o Joe King January 10, 1939 Mr. W. A.{Mr Adams} Robotham, Rolls-Royce, Ltd., Derby, England. Dear Mr. Robotham: This will acknowledge receipt of your letter of December 22nd with regard to exhaust valve guides, and the criticism you have received on the counter boring operation in the upper end of the guide. I fail to understand the reasoning used when stating that the exposed portion of the valve guide would deteriorate more rapidly because of the counter boring. As I told you, the counter bore is about .020 in diameter, and unless I have a decided misconception of things the flow of heat is from the valve into the guide, and the relieved section is not in contact with the guide, although it is exposed to the flame. I might add that the bottom of the counter bore should be a comparatively sharp corner which minimizes the carbon build up on the valve. We have used this construction in automotive work on engines pulling as high as 145 b.m.e.p. without any trace of the condition which appears to be a source of criticism. Incidentally, we do not use steel, but a very good grade of fine grain cast iron or semi steel which has rather good wearing characteristics, particularly in a side valve engine. I believe I mentioned in my previous letter that one of the ways we keep our valve seat temperatures rather low is by using a water distributing tube with metered holes in each exhaust port, which has very materially improved the cooling of the exhaust valve. I am enclosing a blue print of one of the guides which we have used successfully for a great many years. Yours sincerely, E.{Mr Elliott - Chief Engineer} D.{John DeLooze - Company Secretary} Herrick EDH:H Encl. USE THE AIRLINES | ||