Hi folks,
straightforward question. Was the above ever supposed to have a copper head gasket or were they always straight on, head to barrel.
Mine doesn't have one, but i guess that doesn't necessarily make it right.
Alll the manuals i have say re fit "Seal" where fitted, so i assume some ohv engines did have them and some not.
Many thanks.
Many thanks for this…
Many thanks for this information.
It's strange in that with many bikes of the same period, a variety of systems were adopted. Some manufacturers used gaskets on the lands and others such as Rudge used a copper ring sat on the top of the spigot with as much as a 3mm gap between the lands. I suppose so long as it functions with no fretting to the head then all is well. I understand that the ES2 used the gasket on the land principle despite being cast iron mating surfaces just like the 30s M18.
What isnt entirely clear to me is why once the head has been correctly lapped would it ever need doing again. In the case of my m18 I have found the lands to be flat and in good contact but the top of the spigot falling short by about 3 thou.
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Confession time - my Single…
Confession time - my Single has its head sitting on the large land. And within the limits of my depth micrometer, the height of the spigot and depth to its recess match to 0.001" (0.375"). I have no problems whatsoever. I think the design is so nearly balanced that it's not surprising. Unlike a Big Twin.
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At that time the seal was effected by lapping in the spigot on the barrel to the recess in the head. This is where the two grade pot of grinding phase comes into play. Fine for the top of the spigot, Coarse for the land on the barrel.
if your not familiar with this read up on it before you go at it. Care, cleanliness and even pressure all prerequisites for a good seal.