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).
Technical memo discussing engine noise issues related to tappets and cam design.
| Identifier | ExFiles\Box 178\3\ img165 | |
| Date | 11th May 1932 | |
| HS.{Lord Ernest Hives - Chair} ) E.{Mr Elliott - Chief Engineer} ) FROM R.{Sir Henry Royce} DA.{Bernard Day - Chassis Design} ) C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} RHC.{R. H. Coverley - Production Engineer} Le-Canadel. [Handwritten: This is a copy of my original] J.{Mr Johnson W.M.} 3. Mr.Hives memo 5/32 to hand. Much seems to be wrong, but I believe it is not largely due to changes in design, as to the exact proportions needed in production, for great perfection for instance. Engine. Tappets seem to be noisy under all conditions, and therefore not entirely [handwritten: due to] difference of temperature, and to me suggests the cam form is not good for silence. Possibly some little mistake in the toe, ( I believe the tappets are offset, ) we intended at one time to have a long toe to the cam, so that the timing might vary with difference in temperature between push rod and crankcase, but not the noise to any great extent. I have [handwritten: always] felt nervous of high lift cams because of valve spring requirements, [handwritten: & noise] [Handwritten in margin: If new cam forms are made] agree } (I) Long duration. these } (2) Reasonably fast acceleration. are } (3) II2° Degrees, EO. rather late. IC. also later than past- (practice. good. } (4) Two cams alike- 225° CS. with .020 clear. Rapid accelerations, i.e. .020 tappet clearance. Change over, 5° [Diagram showing valve timing with labels IC, EO, 50 degrees, and 10 degrees] cont'd | ||