The ATC 20116 Headbolt Hole Tap (also referred to as a headbolt thread chaser) is a precision tool designed to restore and clean the 11/16-16 UNF head bolt threads in Cummins NH, NT, and N14 engine blocks.
Over time, head bolt holes can collect carbon, corrosion, debris, or slight damage during disassembly. The ATC 20116 allows technicians to recondition the thread surfaces—restoring proper bolt engagement, improving bolt torque consistency, and reducing risk of head gasket leakage due to poor thread alignment.
Key features include:
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Correct 11/16-16 UNF thread size for Cummins NH / NT / N14 engines
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Precision tap to clean and chase threads without excessive material removal
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Durable construction suitable for use in engine rebuild shops
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Helps ensure head bolts can be torqued properly with reliable seating
Made in USA
By incorporating this tap into your rebuild process, you can restore bolt hole threads to near-factory condition, which aids in head installation integrity, gasket sealing, and long-term engine reliability.