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).
Report investigating a recurring issue with a bad set of tappets on chassis 3-AX-107.
| Identifier | ExFiles\Box 131\2\ scan0075 | |
| Date | 21th October 1937 | |
| To By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux} c. Rm.{William Robotham - Chief Engineer} P.Deswell Can this be due to anything but the valves riding RM{William Robotham - Chief Engineer}/GWH.{George W. Hancock - Head Chateauroux}/V/N.21.10.37 Rm{William Robotham - Chief Engineer} 111B Chassis 3-AX-107 - Mileage 10,722. There is another very bad set of tappets taken from the above chassis which Cricklewood are forwarding to you. The car was in the Depot in June of this year for the modification to valve guides, but the bottom tappets were not examined. The mileage then was 6,696. The well of the camshaft was overflowing with oil, so the theory of the camshaft being dry can be dispersed with. This is the first time that Cricklewood have taken the complete tappet units off since I tackled them on there method of removing the tappet guide. There is no proof in the statements made of camshaft being short of oil, as they have not been able to see the condition. A feature which may have a bearing on the tearing up of the tappet faces is ( as was demonstrated to me) the tappets are tight in the guides at the bottom. The guide at this position is the bore in the aluminium block. The alignment of the spindle hole in the steel guide and that of the aluminium bore do not in many cases line up. If the tappet is taken out and turned round half a turn, it will not enter, or if it does it is tight. Without turning the tappet round many are on the tight side. It probably is caused by slight growing of the aluminium metal, but it must place a load on the tappet which is not allowed for. The ones I saw at Cricklewood yesterday were certainly tight in the guides. Is the hole for the tappet spindle bored at the same time that the outer diameter of the steel guide is machined. If not this could cause the misalignment. With a view to trying to help in the matter of the tappets, I am forwarding to you an exhaust rocker and inlet rocker, which are rubbing surfaces which have been taken of an old Bentley 1924-3 litre, for your benefit. They are the original cam pads and have run 128,000 miles as near as they can ascertain. I saw the camshaft and there is hardly any wear noticeable I have got them to put the loads exerted by the valve spring as a matter of interest. The blow upon opening will be greater. Cont'd.{John DeLooze - Company Secretary} | ||