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).
Recommendation to fit Aerolite pistons and instructions for chalk testing existing pistons for cracks.
| Identifier | ExFiles\Box 27a\1\ Scan352 | |
| Date | 16th January 1936 | |
| x 1245 W/P - Sr. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KW.16.1.36. B-179-AE. Mr. F.{Mr Friese} Edmond-Blanc. Sr/VA.3/ET.11.1.36. If you have to re-bore this car we would certainly recommend that you fit Aerolite pistons. If you do not have to re-bore, we recommend that you chalk test the pistons and if there are no signs of cracks, re-fit them. The places where cracks are likely to occur are - (1) On the top side of the gudgeon pin boss. (2) Through the holes drilled in the scraper ring grooves. (3) In the webs of the piston crown. The method of chalk testing is to heat the pistons in paraffin up to 90-100°C., dry them carefully, and then immerse them in French chalk. The paraffin oozes out of any cracks and shows where they are. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||