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).
Fitting, testing, and subsequent adjustment of aluminium pistons in a car engine.
| Identifier | ExFiles\Box 35\2\ scan 016 | |
| Date | 15th May 1916 | |
| R.R. 288A (400 T.) S.C. 539. 15-5-16; G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. X2748 Handwritten note: Comm. Briggs to take the car for tomorrow's race. Clear & will be discussing with him. R from EH. c. to J c. to Sy c. to W'O'R for EH. c. to Hy{Tom Haldenby - Plant Engineer} c. to H.{Arthur M. Hanbury - Head Complaints} EP{G. Eric Platford - Chief Quality Engineer}19/W26916. Re. Aluminium Pistons for the Car Engine. We have now fitted in Commander Briggs' Car, 64LB, a set of aluminium pistons, similar to those fixed in 49GB, drg. No. E.6806B. These pistons are ground taper with .006" clearance on the skirt and .010" clearance on the body of the pistons. There was also some eccentric grinding done at the ends of the gudgeon pins of about a 60° angle, making a maximum clearance of .014". The skirt was left circular, i.e. the space was 1" deep between the scraper ring and the bottom of the skirt. After running, however, it was found that the pistons in this state were too tight. The tightness appeared to be generally on the skirt, and I believe the body of the pistons could have done with less clearance to advantage. (I suggest the next set of pistons we make experimentally should be made with the piston clearance at right angles to the gudgeon pins .008" only.) The engine was dismantled and the piston eased slightly in hard places, this operation being repeated until it was found that the pistons were free with the minimum amount of clearance. | ||