The ATC-8705 thread insert is engineered for restoring worn or damaged head bolt holes in Cummins 855 / NH / Big Cam engine blocks. This insert features a long internal thread of 11/16"-16 TPI and an exterior dimension of 13/16"-16 TPI, with an overall length of 3.25". Works with Apex/Monaco/ Porta-Tool Thread Kits
Used when the original threads are stripped, corroded, or otherwise compromised, the LS-8705 allows technicians to install a durable internal thread that maintains proper bolt retention and alignment—restoring structural integrity without machining out the original boss. This insert is perfect for rebuilds where preserving block strength is essential.
Key Features & Benefits
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Restores original 11/16"-16 internal thread in Cummins 855 / NH Big Cam blocks
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Exterior thread is 13/16"-16 TPI Standard Reamer and Tap used from kit
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3.25" length ensures deep-thread engagement in longer headbolt holes
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Enables repair of stripped or cross-threaded holes while retaining block utility
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Ideal for engine rebuilders, repair shops, and fleet maintenance operations
Typical Applications
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Repairing head bolt holes during overhauls of Cummins 855 / NH / Big Cam engines
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Salvaging blocks with damaged bolt threads without full re-machining
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Use in high-stress or heavy-duty diesel rebuilds where bolt retention is critical
