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).
Standardisation of parts for pistons with reduced depth of top land on the 25/30 HP model.
| Identifier | ExFiles\Box 171\5\ img066 | |
| Date | 15th November 1938 | |
| RR 755A (10H) (49968) 19/10/37 C.E.Co. LS COMPLETED 12.1.39. 25/30 H.P. STANDARDISATION OF PARTS Description TH. PISTONS WITH REDUCED DEPTH OF TOP LAND. Date Issued 15.11.38 Sheet No. W.14. Drg. No. ECD.911 L.O.P.S. Purpose: To overcome trouble experienced on 25/30 of the top land seizing and breaking away. Brief Report and Remarks: The summary of the above mod. is a reduction in the depth of the top land from .250 to .200 and an increase of .002 on the dia. of the top land. Regarding the former, this dimension reverts back to the 3½ litre R.R. pistons on which the above trouble was not experienced. In order to obtain exaggerated conditions we have run pistons with .150 top land depth without any trouble. 27.G.VI is being fitted with ECD.911 pistons and will have completed 10,000 miles before pistons are on production. Other cars to be fitted with similar pistons as they become available. in Cost: £ No difference. GRL 13/12/38 Cost of Tools £15.0.0. Production Position and Comments: Pistons with reduced depth of top land, to overcome trouble with top land seizing and breaking away, can be introduced at the 1st. chassis in 'C' series without scrap. There is no difference in Factory cost, but new tools value £15.0.0d. are required. RHC.{R. H. Coverley - Production Engineer} Authorisation to Proceed. Introduce on the 1st Chassis in C Series. Signature SS{S. Smith} Date 9/1/39 Signature HS{Lord Ernest Hives - Chair} Date 9/1/39 | ||