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 discussing automatic valve-tappet clearance adjustment, with reference to Cadillac and a specification from Royal Lee, as well as valve springs for the PI model.
| Identifier | ExFiles\Box 19\3\ Scan144 | |
| Date | 20th January 1930 | |
| x7772 ROLLS-ROYCE OF AMERICA, INC. SPRINGFIELD, MASS. OY-3 Jan. 20, 1930 RECEIVED Mr. E.W. Hives, Rolls Royce, Ltd., Derby, England. Cc- Mr. Southern(Engl) Mr. Soutter Mr. Burton Mr. Allen Mr. Ross Mr. Ainsworth Dear Mr. Hives: VALVE GEAR 1. Automatic valve-tappet clearance adjustment is just now the "topic of the hour", brought about by standardisation of an automatic compensator on the sixteen cylinder Cadillac. Enclosed specification No. 1,644,840 from Royal Lee is an adaptation to simple valve gear on L-head engines. I thought it might interest you to build some tappets this way and try them. The Cadillac uses eccentric bushes much like ours on PI, but these are turned by an oil-damped spring plunger to always take up the clearance completely. You have doubtless seen descriptions of this but in case you have not a copy, I attach sheets from Automotive Industries of Jan. 4th. 2. Cleveland Wire Spring Co. after several months of test have achieved some springs for PI of which the characteristic is shown in attached chart from Btn., compared with E-78071. To get these they built up a trial valve gear consisting of a short length of our PI camshaft with push rod, rocker mechanism, valve, guide and seating, etc., complete. They run this outfit with a high speed instantaneous vision apparatus, at all probable speeds and analyse the results. - continued - | ||