To check a cylinder head for twist and warpage, which tools are used together?

• A. Steel straight edge and feeler gauges
• B. Torque wrench and micrometer
• C. Caliper and dial indicator
• D. Feeler gauges and pliers

Answer: (A)

Checking a cylinder head for twist and warpage is all about establishing a true reference plane and measuring any gaps against it. A steel straight edge gives that flat reference across the head’s surface, and feeler gauges detect any separation between the straight edge and the head at various points. By laying the straight edge across the head in multiple orientations (front-to-back, side-to-side, and across the center) and inserting feeler gauges into the gaps at key locations, you can see whether the head sits flush. If any gap is larger than the manufacturer’s tolerance, the head is warped or twisted.

This approach is preferred because it directly reveals flatness differences across the entire surface, which must seal properly against a gasket. Other tools aren’t as well suited for this specific check: a torque wrench and micrometer measure torque and thickness at isolated points rather than overall surface flatness; a caliper and dial indicator can be used for other measurements but typically require a more complex setup to assess warp, whereas a straight edge with feeler gauges is the standard, straightforward method; and feeler gauges without a reference like a straight edge don’t provide the necessary baseline to judge flatness, while pliers aren’t measurement tools.