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).
Test report on Ph.II Silent Tappets and E.82448 Camshaft.
| Identifier | ExFiles\Box 17\6\ Scan320 | |
| Date | 27th November 1934 | |
| x7060 27.11.34. Ph.II Silent Tappets - E.82448 Camshaft. (Tests carried out 23.10.34 to 6.11.34). BJ55 Unit was built up to the following specification (RHC{R. H. Coverley - Production Engineer}/WSC.{W. S. Cassel}13/EP.{G. Eric Platford - Chief Quality Engineer}19.10.34) :- Cyl: head to LeC.3960-3959 with lightened valves. Camshaft E.82448 with new forms for 4th and 6th exhaust cams (see Hs{Lord Ernest Hives - Chair}/Smth.23/KW.21.6.34.) Large semi-expanding carburetter. Valve springs E.85666 (85 lbs. on seat, 155 lbs/in. rate). Silent tappet adjusters as specified in Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}2/KW.17.9.34. The first set of tappets tried had a plunger clearance of .00075. The valve gear was quiet when slow running, but No. 1 inlet valve was held off its seat at speeds higher than 3250 r.p.m., the other valves being O.K. up to 3500 r.p.m. This effect persisted on interchanging Nos. 1 and 5 plungers and casings, thus demonstrating that the hydraulic unit was not responsible. The load required to open each of the valves was found and No. 1 spring load was found to be the lowest by a small amount. This spring was then changed for No: 5, the loading on No. 1 then becoming the largest of the 12. No. 1 inlet valve was still held open at speeds higher than 3300 r.p.m. A new set of tappets was now fitted, with .00125 plunger clearance. With these No. 1 inlet valve was O.K., but No. 6 exhaust valve was held open at speeds greater than 3400 r.p.m., but not sufficiently to cause an appreciable drop in power at 3500 r.p.m. A .050 packing washer under this spring enabled 3500 r.p.m. to be reached without any valve riding. The large clearance units were as steady and quiet at low speeds as the others. Attached are curves showing power comparisons with E.80070 & E.82448 camshafts. Hs{Lord Ernest Hives - Chair}/F.Ll.Smith. | ||