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).
Measurements and issues with a Bentley B-8-GA cylinder block following complaints of excessive oil consumption.
| Identifier | ExFiles\Box 130\2\ scan0151 | |
| Date | 24th September 1936 | |
| Copies sent to Swdl.{Len H. Swindell} x4175 Gry.{Shadwell Grylls} Mths.{Reg Matthews} To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} Levallois, Sept. 24th, 1936. Bentley. I enclose measurements taken of the cylinder block of B-8-GA. Sr. complained of excessive oil consumption after the engine had been refitted up with new bearings and new piston rings fitted. (approximately 300 M.P.G.) The actual wear at the top is not great for the mileage, but the wear just above the bottom of the cylinder block (i.e. practically in a line with the water jacket), seems to point out distortion with the tightening up of the cylinder block or bad grinding in the first place. It is very similar to the block I had sent up to you from Kingsbury. I have examined the piston rings. The two top rings of the pistons had worn down. (after approx. a 1,000 miles) to a sharp edge, but the scraper ring one could still see a fine chamfer at the scraping edge and would not act correctly as a scraper. While we are getting this uneven shape of the bore one cannot expect rings to do their work correctly. Fitting the L shaped ring is apparently getting over to an extent faulty grinding, or honing. Honing a cylinder bore is alright so long as the bore is true; otherwise it simply follows the contour of the bore. We have just proved this on this particular block. By just running the honing stone down lightly it shows up the uneveness of the cylinder wall. Sr. having received permission from you, is fitting one L shaped ring, but I feel that the job can be made alright by attention to the rings and the bore. | ||