Slipped cylinder liners on a Big Cam 855 or N-14 are usually the result of a fretted block deck. The ATC 2200-72A Shim Cutter Plate provides the precision-guided machining path needed to restore a flat seating ledge.

The Challenge of In-Frame Counterbore Machining

On classic high-horsepower Cummins 855 NH and N-14 diesel engines, the block counterbore ledge takes the brunt of combustion force. Over millions of cycles, the liner flange vibrates, eroding the cast iron block—a condition known as "liner drop." If the liner settles too low, head gasket failure is inevitable. To fix this in-frame, technicians utilize a Porta-Tool style counterbore cutter. However, the accuracy of the cut depends entirely on the adapter plate. The ATC 2200-72A is engineered specifically for **5.5" (5 1/2) bores**, ensuring the cutting bit tracks perfectly concentric to the cylinder axis. By providing a rigid, zero-play interface between the tool housing and the block, this plate allows you to machine a perfectly horizontal landing for repair shims.

• Platform-Specific 5.5" Geometry – Designed exclusively for the 5-1/2 inch bore specifications of Cummins 855, NH, and N-14 engines.
• Direct Legacy Tool Compatibility – Fits perfectly onto Porta-Tool cutter assemblies, serving as a high-durability alternative to **PT-2200-72A**, **PT-2250B**, and **M50133** components.
• Absolute Machining Stability – Locks the cutter head securely to prevent tool-chatter, ensuring a mirror-flat finish on hard cast iron ledges.
• Cost-Effective Deck Restoration – Enables shops to save expensive engine blocks that would otherwise require complete removal and external machine shop service.
• Shop-Grade Heavy Alloy Build – A substantial 8.00 lbs machining plate forged from premium tool-grade steel to resist thermal expansion and warping during deep cuts.

Eradicate Liner Drop. Restore Your Compression.

The ATC 2200-72A Counterbore Cutter Plate is a vital component for independent diesel machine shops, commercial fleet centers, and heavy equipment rebuild bays. Maintain absolute control over your liner protrusion heights and lock in a million-mile seal.

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