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).
Investigations into valve gear issues and noise problems on a 25/30 HP car.
| Identifier | ExFiles\Box 108\1\ scan0419 | |
| Date | 25th February 1938 | |
| To. Rm.{William Robotham - Chief Engineer} c. Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} [Signature] CHATEAUROUX. 2/.25.2.38. 600a ? 26.G.VI.- 25/30 HP. Valve Gear. Thank you for your memo Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}II/JH.23.2.38. We will fit the following parts when to hand. 1) Six new exhaust valves, and check seats for sinkage as an alternative explanation for loss of tappet clearance. 2) Six E.W.1428 Valve springs to Nos. 7 - 12 3) Twelve modified bottom tappets and existing 5/16" push-rods. We will also measure the valve spring length both with the old and new valves. Regarding valve bounce, we have noted your remarks and made further investigations as a result of which we must admit that we have been mistaken about the bad valve bounce and consequently misled you. The very bad clatter which comes in at 82 m.p.h. on the speedometer is not valve bounce. We do not know what it is, but have made the following observations concerning it. 1) It can only be heard from inside the car with a floorboard removed, and occurs every time 82 m.p.h. on the speedometer is reached at full throttle on top gear. It is quite an alarming noise and continues up to full speed, but is loudest when it first comes in. 2) It cannot be reproduced in the garage. 3) It cannot be heard when sitting on the mudguard with the bonnet open, at the same time that it is audible to the driver with a floorboard removed, i.e. at 82 m.p.h. speedometer speed on the road. Regarding the slight valve bounce reported at 75 m.p.h. on the speedo. when you asked for the valve bounce speed, we ran the car up on the jacks and at 75 m.p.h. a definite clatter came in which we have confirmed comes from the valve gear. | ||