Valve lash is defined as the clearance between which parts when the valve is closed?

Valve lash is defined as the clearance between which parts when the valve is closed?

• A. Valve stem and valve guide
• B. Valve lash
• C. Rocker arm and valve spring
• D. Valve face and valve seat

Answer: (B)

Valve lash is the small gap in the valve train that exists when the valve is closed. This clearance is the gap between the valve stem and the rocker arm (or cam follower) that actuates the valve. It must be present so that, as parts heat up and wear tolerances accumulate, the valve can still seat fully without sticking or staying slightly ajar. Measuring and setting this lash to the correct spec keeps valve timing consistent and ensures proper sealing at operating temperature. The other parts listed don’t define lash—the gap isn’t between the valve face and seat (those surfaces must seal with little to no clearance), nor is it the clearance between the stem and guide or between the rocker arm and the valve spring.

Valve lash is the small gap in the valve train that exists when the valve is closed. This clearance is the gap between the valve stem and the rocker arm (or cam follower) that actuates the valve. It must be present so that, as parts heat up and wear tolerances accumulate, the valve can still seat fully without sticking or staying slightly ajar. Measuring and setting this lash to the correct spec keeps valve timing consistent and ensures proper sealing at operating temperature. The other parts listed don’t define lash—the gap isn’t between the valve face and seat (those surfaces must seal with little to no clearance), nor is it the clearance between the stem and guide or between the rocker arm and the valve spring.