[Barry Bordes]

Originally Posted by j9fd3s

i'm not sure where this is mentioned, but a new factory apex seal isn't flat, its bowed slightly, so that when its in a working engine and up to temp its flat.

another problem on used housings, this is why they shrink, and why we measure for width, is that the steel liner actually collapses in the compression area, so the center of the housing bows in. its very bad to have leakage between chambers...
mike

Mike, a slightly different interpretation of the housing wear could be that the high temps in the spark plug area cause expansion between the torqued plates which in turn compresses the surface, distorts the face, and chafes the faying surfaces (which causes the undersize housing measurements).

Notice the temps where we want to provide extra cooling are doubled that of atmospheric boiling water.
Barry