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).
Cylinder head nuts for Peregrine & Bensfort engines, debating stud size and materials.
| Identifier | ExFiles\Box 86\1\ scan0003 | |
| Date | 6th June 1932 | |
| X219. E.{Mr Elliott - Chief Engineer} FROM R.{Sir Henry Royce} R1/M6.6.32. C. to SG.{Arthur F. Sidgreaves - MD} WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} HS.{Lord Ernest Hives - Chair} X.4027 X.4553. PEREGRINE & BENSFORT CYLINDER HEAD NUTS. In reply to your memo. E 4/HP4632., I should not consider for a moment departing from our 6 bolt standard. There is no reason why the .250" studs should not be tightened correctly. One uses much smaller sizes than this in the spokes of wire wheels, etc. No doubt it would be better to increase the size to 5/16" at the expense of a small increase in the length but altering the whole engine length, patterns, crankshaft, etc, seems rather serious. Compared with our other cars the .250" stud does not seem to be much overloaded. These could perhaps be made in the improved molybdenum steel. Taking the R.{Sir Henry Royce} engine at nearly 1600 lbs. per sq. in. it is probable that the studs of even the Bensport would not be as heavily loaded as these. I had the impression that we were to supercharge .5 atmospheres, which would therefore be proportionately less than the R.{Sir Henry Royce} engine, and should only put the maximum pressure up 50%. We are trusting to the balance weights to save the crankchamber and crankshaft bearings. We do not think the extra speed will do much harm to the other parts during the occasional extra high speed running. We do not think we can do anything to stop an unskilled person screwing down the nuts badly. Probably a box spanner with a fixed tommy bar, or a slide through rivetted in type, would be all we could do to help. The risk is that people will not go over the studs little by little, increasing the pressure all over the joint slowly. I should mostly fear the studs being drawn out of the cast iron crankchamber. R.{Sir Henry Royce} | ||