twin head gaskets

[Groily]

I can't remember now exactly what it was, sorry, but a tad under 2mm sticks in my mind. Now, if the spigot's .115 and the recess is, say, .075 that ought to mean that any gasket of decent density, however thin (within reason) would do the job, I know. But not so. I don't know how much thinner a gasket gets when torqued down as compared to when measured after the pressure is off again (as in x turns of nut?), but my back of envelope arithmetic, aided by the chance to measure a pile of discarded gaskets from way back when, told me I needed a gasket of c. 2.25mm or c. 0.0875" to be guaranteed safe on this cylinder. Which sat well with the 92-odd thou of the used one that is back in there and keeping oil and the combustion process under proper management. The heads and barrels are correct and in pretty good order, and could even be original pairs although I can't say that no mating surface has ever been skimmed - wherein may lie an issue. I've known or owned the thing for best part of 40 years and nary a top end problem. The previous owner, who still rides it regularly when he visits for some open roads and moules frites, can't recall any previous trouble either. Part of life's rich pageant I suppose . . .