Definition of quantal. 1  1 [Latin quanti how many, plural of quantus] : of, relating to, or having only two experimental alternatives (such as dead or alive, all or none) 2  2 [quantum] : of or relating to a quantum.
3. Engine movement. Another symptom of bad or failing engine mounts is an engine that moves in the engine bay. If the engine mounts are in good condition, they should be able to secure the engine firmly in the engine bay.
Misalignment between the seat and guide causes the valve stem to flex every time the valve closes. Eventually, this flexing leads to metal fatigue and valve failure. When this happens, the counterbore must be remachined (if the head is salvageable) to realign the seat with the guide.