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).
Directive regarding the specifications for replacement piston rings on Bentley and Phantom III models.
| Identifier | ExFiles\Box 103\2\ scan0005 | |
| Date | 7th July 1939 | |
| Md. W/W - Mr. Levallois K.{Mr Kilner} Bdx. Rm{William Robotham - Chief Engineer}/GWH{George W. Hancock - Head Chateauroux} (K) Hy{Tom Haldenby - Plant Engineer}/BPS Hx/SB{Mr Bull/Mr Bannister}7/MG.7.7.39 PISTON RINGS Bentley and Phantom III We are satisfied that 'L' section rings are effective in producing a quick result as regards bedding, and there have been numerous instances where complaints of overoiling have been cured by their use on customers' cars where the conditions of running have not assisted towards quick bedding in of the standard rings. In view of the fact that the normal running after re-boring or replacement of rings produces nothing like the same effect as the unit bed or dynamometer testing of new cars, it is desirable in all cases of service replacement to use the most effective piston rings available, and it has therefore been decided to use 'L' section rings in the standard make-up of all replacement pistons on 3½ and 4¼ litre Bentleys and all Phantom IIIs. For the same reason, high pressure scraper rings should be included, although these will not have such a marked effect as the 'L' section rings. Further, all replacement rings should be tin-plated, as the plating assists towards obtaining a better bed by covering surface defects, also by transference of tin to the cylinder walls helps to reduce bore wear. A chart showing details of rings for replacement in various oversizes is attached. HX/SBSA | ||