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).
The increased tappet clearance for a new camshaft and proposing methods for marking and measuring it.
| Identifier | WestWitteringFiles\A\May1917\ Scan4 | |
| Date | 14th May 1917 | |
| To By.{R.W. Bailey - Chief Engineer} from R.{Sir Henry Royce} c. to J.{Mr Johnson W.M.} c. to EH. c. to EP.{G. Eric Platford - Chief Quality Engineer} X.2553 c. to L. c. to Ov. X 2958. X 2975. X 3001 ORIGINAL. RE TAPPET CLEARANCE. It is intended in the new camshaft that the tappet clearance shall be increased very considerably, so that there is no fear of the roller being tight when it is on the smallest part of the cam. We have therefore extended the foot so that the running clearance when hot will be 15 mils and when cold will be 30 mils for the exhaust. I propose that this shall be engraved on the aluminium of the camshaft casing in good large figures on each side of the centre flange. On one side it will refer to the inlet valve and on the other side to the exhaust valve, giving the clearance suggested when the engine is cold. We think this will be preferable to fitting a plate. It will be lighter and cannot be taken off. Also, one will not have to refer to the Instruction Book. It may be advisable to provide a taper gauge marked in thousandths of an inch with a special line showing the clearance suggested when the engine is cold. Such a gauge would be very useful to show the thickness of the washers to be put on, which, with the new tappet motion [handwritten: Bolt], will require the camshaft to be removed or lifted to enable these to be fitted. R, | ||