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).
Overoiling issue on chassis 115-MC and disputing micrometer measurements.
| Identifier | ExFiles\Box 47\1\ Scan357 | |
| Date | 25th October 1926 | |
| W/P - Ps. C. to Hs.{Lord Ernest Hives - Chair} X 4117 His RECEIVED OCT 25 1926 Hm{Capt. W. Hallam - Head Repairs}4/W25.10.26. Re Chassis No. 115-MC - M.{Mr Moon / Mr Moore} Poberejsky. Ps/Crn2/13.10.26. We have noted with interest your memo with report on chassis 115-MC. dated 10.10.26 attached, also the sketched dimensioned drawing. It would appear from the aforementioned that in spite of two sets of the latest type Piston Rings you did not succeed in overcoming the overoiling trouble on chassis 115-MC, and eventually this trouble was overcome by refitting the Engine Main Crank Shaft and Connecting Rod Bearings. The measurements on the sketch we take it are as they were found to be before you refitted the Engine Bearings. It is quite obvious that the dimensioned sketch you have sent is wrong, or your micrometers are inaccurate. In the first place, according to your figures the only discrepancies in our manufacturing limits on a new chassis are as follows :- Nos. 5 & 6 Main Journals are .0005" under limit. No. 3 Main Bearing is .001" large. Nos. 2, 4 & 6 Connecting Rod Bearings are .003" .002" and .002" respectively large. This would represent extremely good condition for a car which had run about 5,000 miles. The amount of oil escape from such clearances would not constitute overoiling - so our experience goes to prove. We have therefore, come to the conclusion that your micrometer measurements are not reliable, and we know how difficult it is to have reliable measurements by internal and external micrometer measurements. Moreover, if the overoiling was cured by refitting the bearings we consider it goes to prove that you should keep your micrometers more accurately checked. The dimension you give on No. 7 Main Journal shows us that you are at fault because the maximum dimension for this journal is 2.6245" with a .001" minus limit. Another point which we wish to bring to your notice is why your Foreman did not carry out the test which we advised you of in our Hm{Capt. W. Hallam - Head Repairs}15/W26.8.26, wherein we referred to | ||