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).
Technical memorandum discussing the causes and potential solutions for engine bore wear.
| Identifier | ExFiles\Box 178\2\ img038 | |
| Date | 4th April 1940 | |
| Serial No 65 OY/1/hc/April 4-40 April 4 1940 Rolls-Royce Ltd. Derby, England Rm{William Robotham - Chief Engineer} Yours Rm.{William Robotham - Chief Engineer}6.ML 12-3-40 Car Work Bore Wear. I have not seen Alex on bore wear, but would not jump to the conclusion that he is entirely cheating. There are some acknowledged facts:- 1. Quick warm up reduces wear and thermostat-controlled exhaust heating system is good for this. 2. Cast iron pistons (Chevrolet and Pontiac) are acknowledged to be vastly better for bore wear, especially under dust conditions. Aluminum pistons are perfect laps. 3. Nitrided bores are much better. Ford bores do not wear. At the Proving Ground they distort and clamp the pistons, but in an average passenger car and taxicab service, they seem good. Beardmore diesels on Canadian National railcars show excellent results from nitrided bores. 4. The pernicious habit of British chauffeurs of "warming up" the engine when cold instead of getting busy and using the damn things may contribute to bore wear. 5. Extra lubrication at starting and "cool" oilpans, are known to be desirable. 6. Splash lubrication for starting (Chevrolet and Hudson) has shown its value for years on Proving Ground tests. Also under suspicion is the habit of running cast iron bores with piston rings of similar materials. Did I tell you Ralph Teetor was playing with edge-bedding steel rings? Dave Wallace's "superfinish" experiment of wringing a steel slug on to the end of a steel bar is a warning to all and sundry of the effects of running smooth similar materials together under high load and low velocity. Does not apply to C.I. pistons because these have low load at low velocity. But I don't think there will be anything quite as good as your chrome-plating of top of bore. How do you propose to do this? Counterbore .002 to .004 big on diam., chrome plate deep and then hone? A mere flash coat of chrome will tear loose, won't it? | ||