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).
Continued notes on cylinder head gaskets, push rods, and rocker bushes, detailing test results and component specifications.
| Identifier | ExFiles\Box 97\4\ scan0253 | |
| Date | 7th December 1938 | |
| -4- CYLINDER HEAD GASKET - Cont'd.{John DeLooze - Company Secretary} With the present .062 thick section big end bearings however, in the event of a bearing failure, the piston which is .030 below the block would just hit the head with the possibility of further damage. To avoid this and retain the .030 gasket it is necessary to have the pistons .060 below the block as outlined in the memo Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}3/JH.2.12.38. PUSH RODS. These were in .4 carbon steel forgings as supplied by The Belgrave Engineering Co. and heat treated giving a Brinell of approx. 300. As bought for 5d. per rod they represent a factory cost saving of 10/- per unit, other than being sand blasted are unmachined externally, also the small sphere at the base of the rod is not ground and the large spherical seating at the top of the rod is not lapped in. This external finish is identical to the rockers themselves. These have proved very satisfactory, having completed the 20 hours endurance and 18,000 miles running without any noticeable wear. A standardisation sheet is being issued to incorporate on Wraith when convenient and is included on Bentley V L.O.F. ROCKER BUSHES. Vandervell strip whitemetal lined bushes completed the above test satisfactorily, and other than generally making for quieter valve gear, bought out for 2d. each, represent a saving of approx. 3d. per bush or 3/- per set compared with our std. BZ/FC. bushes. These are pressed in the rocker at the recommended interference fit of approx. .003 and reamed to requisite bore, the locking pin at present used being deleted. Like the push rods, a sheet is being issued to incorporate on Wraith and is included on Bentley V.{VIENNA} L.O.F. | ||