What is the approximate maximum allowable warpage of a cylinder head?

• A. 0.004-0.006 inches
• B. 0.010-0.020 inches
• C. 0.001-0.003 inches
• D. 0.008-0.010 inches

Answer: (A)

Maintaining the cylinder head’s flatness is essential for a reliable seal with the head gasket. When the head warps even slightly, the gasket can’t seal evenly across the surface, leading to leaks, coolant loss, or compression problems. The commonly accepted maximum allowable head warpage is about 0.004 to 0.006 inches. If you measure more warp than that, the head usually needs to be resurfaced to restore flatness and ensure a proper seal. Measuring in the smaller range, like 0.001–0.003 inches, might be acceptable in some engines but is tighter than the standard maximum for many manuals. Ranges such as 0.010–0.020 inches or 0.008–0.010 inches are generally beyond what the gasket can reliably seal, signaling the head should be resurfaced or replaced.