A member of our local TSSC (UK Spitfire) club had his 1969 Spifire MK3 FDxxxx engine overhauled by a garage in 1998. The overhaul included a +0.020" cylinder rebore, new pistons, and a crankshaft -0.010" regring with new shell bearings. This year, after 8000 miles, he complained that the engine was using a lot of oil and seemed to be very noisy. He contacted the garage who did the rebuild and they said that a rebored engine did use oil until the parts run-in correctly, and in any case the work was more than 12 months ago and the job was now out of guarantee.
   My son and I were asked to look at this engine and found it to be misfiring and with a smokey exhaust. We tested the compression and found one cylinder to be very low (3 bar). We removed the cylinder head and found the valves all to be in good condition and they appeared to be sealing properly but one chamber was black. We removed the piston from this black cylinder. It is the one in the photograph. We inspected all the pistons and found the other 3 to be damaged.
   We fitted a new set of pistons and rings and reassembled the engine. Upon test we found the carburettor petrol mixture very weak and the ignition too far advanced. We believe this error to be the cause of the pistons melting. The engine has now gone another 4000 miles with no further problems. The ignition timing and carb tuning have now been rechecked and found to be correct.
   Moral of the tale - ensure carbs and ignition are checked a few miles after a rebuild. We will never know if the engine re-build garage was at fault.