Once the engine speed rises above idle, the exhaust volume and extra heat will make the bimetal spring lose more tension and the flap valve will go to the full-open position. If you're a brave soul, try propping the hood partway open and riding the fender to watch the valve while a friend takes a drive around the block!
LOL!
Jerry
Its the 21st century Jerry. They have this gizmo called a Go Pro now for such things. They also have a thing called Google where you can look up stuff like Go Pro.
Your pal
