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).
Causes of noisy engine tappets, their relation to cam design, temperature, and potential solutions.
| Identifier | ExFiles\Box 178\3\ img161 | |
| Date | 11th May 1932 | |
| COPY. HS{Lord Ernest Hives - Chair}/RM.{William Robotham - Chief Engineer} ) FROM R.{Sir Henry Royce} E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} ) (At Le CanadelHenry Royce's French residence). C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} C. to BY.{R.W. Bailey - Chief Engineer} RHC.{R. H. Coverley - Production Engineer} re. J.3. Mr.Hives' memo of 4.5.32 to hand. Much seems to be wrong, but I believe it is not so 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 due to difference of temperature, and to me it suggests that 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 always felt nervous of high lift cams because of valve spring requirements, and noise. (1) Long duration. (2) Reasonably fast acceleration. (3) 112°, E.O. rather late, I.C. also later than past practice. (4) Two cams alike - 225°CS. with .020 clear:) Handwritten note next to points 1-4: 'I agree these are good, if new cam forms are made.' Rapid accelerations - i.e. .020 tappet clearance. [Diagram showing a circle with angles 50° and 40° labelled I.C. and E.O. respectively. Text next to it reads 'Change-over 50'] I had the impression that Mr.Lovesey got good HP. without high lift. It will be understood that no lift, no noise, and therefore the higher the lift the greater the noise. NOVEL. If difference of temperature is the trouble it has occurred to me that we might put an oil pipe the full length of the head inside, so that the oil would be the same temperature as the Cont'd.{John DeLooze - Company Secretary} Top right of document: Rec'd & despatched from WW. 20.5.32 Handwritten numbers: x5770. x5090. x634. | ||