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).
Instructions for engine bearing maintenance, modifications, and specific notes for a 3½ Litre Bentley.
| Identifier | ExFiles\Box 115\1\ scan0289 | |
| Date | 12th February 1937 guessed | |
| - 2 - Depot Sheet No. Hd.{Mr Hayward/Mr Huddy}333. Continued:- Wear of the main bearings with sinkage can be taken up in the normal way by reducing the shim in its overall thickness by the requisite amount. 2. Whilst the lower half is removed the connecting rod bearings should be inspected. If there is any sign of the Hall's metal facing breaking away from the shims these should be replaced by shims in solid R-R.56 aluminium. Unless it is necessary to take up any wear then the R-R.56 replacement shims should be made exactly the same thickness as the ones removed. Providing that the bearing surface is good, without signs of failure, there is no necessity to remove the connecting rods which entails removal of the head and de-carbonising etc. 3. If for any reason a new set of main bearings has to be fitted, it is important to note that the new intermediate main bearings should incorporate oil grooves with slightly larger dimensions than formerly. The diameter of the new groove is 2.350" and it is .125" wide. This alteration is being brought on Production immediately. 4. If the crankshaft is removed the opportunity should be taken to drill additional oil holes in the main journals. At present there is only one hole in each journal but an extra hole diametrically opposite this hole should be drilled in each journal. The hole is .218" diameter. As the crankshaft is nitro-hardened a small flat will have to be ground to get through the hard skin. 5. In the event of new big end bearings being required, these should be in Hall's metal with R-R.56 shims. 3½ LITRE BENTLEY. White metal main bearings which were standard, have no grooves in the intermediate main bearings. Whenever a new set of main bearings is required white metal bearings should be fitted and it should be noted that the intermediate bearings should have a groove 2.300" diameter x .100" wide. -continued- | ||