Which component prevents undesirable side-to-side movement of the valve within the cylinder head?

• A. Valve guide
• B. Valve spring
• C. Poppet valve
• D. Air intake system

Answer: (A)

Valve guides provide a precisely bored passage through the cylinder head that surrounds the valve stem, keeping the valve centered as it moves. This constrains side-to-side wobble and ensures the valve travels straight up and down, so it seats properly and seals when closed. The valve spring supplies the closing and opening force, but it doesn’t control lateral movement. The poppet valve is the actual sealing element, not its guidance, and the air intake system handles air flow, not valve alignment.