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).
The wear of valves and guides after a 10,000-mile test, comparing broached and reamed finishes and tabulating measurements.
| Identifier | ExFiles\Box 171\3\ img242 | |
| Date | 20th August 1924 | |
| To Hs.{Lord Ernest Hives - Chair} from RHC.{R. H. Coverley - Production Engineer} RHC{R. H. Coverley - Production Engineer}3/LS.20.8.24. RE - VALVES & GUIDES ON 98 NK. We have examined the Valves and Valve Guides (made in Phos: Bronze) which were fitted to the above Car for 10,000 mile Test. The Valve Guides in the Front Cylinders No's 1-6 were Broached, this operation was carried out by merely pushing a .437 dia: steel ball through Guide which has the effect of not only toughening the surface, but gives a good burnished finish. Bore of Guides was left .0005 small for Broaching. The Rear Block No's 7-12 were Reamed finish, and whilst the wear seams about the same in each case, we are of the opinion that the Broached Guides are in better condition. All Guides were made the same diameter in bore which makes the clearances for Inlet and Exhaust alike .004. The standard clearance is, Inlet Valves .004, Exhaust Valves .006. Below chart giving particulars of wear on Valves and Guides. Firths Silchrome Valves E.24285. Org: dim: | 1. | 2. | 3. | 4. | 5. | 6. | 7. | 8. | 9. | 10. | 11. | 12. A.{Mr Adams} | .433 | 431 8 | 4325 | 4325 | 432 | 4325 | 4325 | 4325 | 4325 | 4325 | 4327 | 4325 E.{Mr Elliott - Chief Engineer} | .433 | 4315 | 432 | 432 | 432 | 432 | 432 | 431 7 | 4325 | 4325 | 4325 | 432 Valve Guides E.21421. Orgl: dia: | 1. | 2. | 3. | 4. | 5. | 6. | 7. | 8. | 9. | 10. | 11. | 12. A.{Mr Adams} | .437 | 437 | 437 | 437 | 437 | 437 | 437 | 437 | 437 | 437 | 437 | 437 B. | 437 | 4382 | 4372 | 4382 | 4372 | 4382 | 4372 | 4372 | 437 | 4375 | 4385 | 4372 Some Guides had closed in about 1/4 to 1/2 thou at the top, but this does not appear to have made any difference. RHC.{R. H. Coverley - Production Engineer} | ||