287. Engine Innards
I managed to get to the Shuttleworth Collection today, and found substantial progress on the engine. The cylinders are back from relining, and Phil is delighted with the standard of work. the cylinders and liners are so thin that you can squeeze the sides together with your hands by 0.004in (4 thou, in engineer’s speak). This might not sound masses, but the bottoms need to be larger than the tops by exactly that amount.
That’s the reason the cylinder have to be fixed in a special jig to hold them rigid, otherwise the pressure of the honing tool would distort the cylinder wall and wreck the whole operation.
Because of that taper (or choke), the bores have to be honed by hand, and apparently they are accurate to two tenths of a thou. All nine cylinders, all round, and all the way up the bore – an even taper. It’s an astonishing achievement. we await the bill…
The holes in the pistons for the gudgeon pins (wrist pins, if you’re American) are slightly undersize and have gone away to be honed, but should be back in a day or so.
So here are some pictures of those gorgeous cylinders, and the state of reassembly of the rest of the engine.