Originally Posted by RCAlyra2004

BINGO... That is exactly what happens..well done

in some cases the shaft of the valve expands too.

For an Iron or even a brass(close enough) shaft the expansion rate is .0000063 per inch of shaft per degree rise in temperature from the norm.

So for a valve with a 1.75 inch long shaft (purty normal length) it will expand
.0017 inches. That is almost two thousandths of an inch (towards closed)