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).
Blueprint detailing piston dimensions and ring gaps before and after use.
| Identifier | ExFiles\Box 83\2\ scan0041 | |
| Date | 21th May 1937 | |
| B4 UNIT PISTON DIMENSIONS RELIEVED PORTION BEARING PORTION AEROLITE PISTONS IDENTIFICATION Nº M.12. PISTONS 1.5 & 6 HAVE DONE 16,000 MILES IN FRANCE. PISTONS C.53, 305 & 18 HAVE DONE ONLY 500 MILES PISTON No. | A | B | C | D | E | A1 | B1 | C1 | D1 | E1 | RING GAPS. 1ST 2ND 3RD | NOTES ---|---|---|---|---|---|---|---|---|---|---|---|---|--- 1 | BEFORE | 3.483 | 3.4826 | 3.4822 | 3.4825 | 3.487 | 3.4835 | 3.4825 | 3.4822 | 3.496 | 3.5005 | .008 | .008 | .009 | NO PISTONS WERE CRACKED. | AFTER | 3.4829 | 3.4822 | 3.4817 | 3.482 | 3.4861 | 3.4835 | 3.4822 | 3.4817 | 3.4953 | 3.5002 | .018 | .013 | .019 | DIFF. | -.0001 | -.0004 | -.0005 | -.0005 | -.0009 | NIL | -.0003 | -.0005 | -.0007 | -.0003 | +.010 | +.005 | +.010 5 | BEFORE | 3.4827 | 3.4823 | 3.4818 | 3.4830 | 3.486 | 3.4827 | 3.4823 | 3.4818 | 3.496 | 3.5002 | .008 | .008 | .009 | AFTER | 3.4829 | 3.4828 | 3.482 | 3.4818 | 3.486 | 3.4831 | 3.4828 | 3.482 | 3.4953 | 3.5003 | .015 | .010 | .019 | DIFF. | +.0002 | +.0005 | +.0002 | -.0012 | NIL | +.0004 | +.0005 | +.0002 | -.0007 | +.0001 | +.007 | +.002 | +.010 6 | BEFORE | 3.483 | 3.4825 | 3.4817 | 3.483 | 3.486 | 3.483 | 3.4825 | 3.4817 | 3.496 | 3.5002 | .008 | .008 | .009 | AFTER | 3.4828 | 3.4825 | 3.482 | 3.4818 | 3.486 | 3.4832 | 3.4822 | 3.4818 | 3.495 | 3.5001 | .021 | .011 | .023 | DIFF. | -.0002 | NIL | +.0003 | -.0012 | NIL | +.0002 | -.0003 | +.0001 | -.001 | -.0001 | +.013 | +.003 | +.014 C.53 | BEFORE | 3.4807 | 3.4807 | 3.4806 | 3.4841 | 3.4859 | 3.4808 | 3.4803 | 3.480 | 3.4976 | 3.4981 | | | | THE ABOVE GAPS WERE MEASURED | AFTER | 3.480 | 3.4799 | 3.4797 | 3.4832 | 3.485 | 3.480 | 3.4798 | 3.4792 | 3.4969 | 3.498 | | | | BY PLACING THE RINGS IN THE | DIFF. | -.0007 | -.0008 | -.0009 | -.0009 | -.0009 | -.0008 | -.0005 | -.0008 | -.0007 | -.0001 | | | | UNWORN PART OF THEIR RESPECTIVE | | | | | | | | | | | | | | | BORES AND INSERTING FEELER-GAUGES 305 | BEFORE | 3.4818 | 3.4817 | 3.481 | 3.4838 | 3.4857 | 3.482 | 3.4812 | 3.4803 | 3.4976 | 3.498 | AFTER | 3.4817 | 3.4813 | 3.4808 | 3.4833 | 3.4853 | 3.4819 | 3.4812 | 3.4801 | 3.497 | 3.4978 | DIFF. | -.0001 | -.0004 | -.0003 | -.0005 | -.0004 | -.0001 | NIL | -.0002 | -.0006 | -.0002 18 | AFTER | NO RECORD ROLLS-ROYCE LTD. PRINT ROOM. 21 MAY 1937 DERBY. | ||