Piston Ring 4.275FileFit Bore 1.0 1.0 2.0mm

The Piston Ring 4.275 File Fit Bore 1.0 1.0 2.0mm (SKU: MAH4275MS-112) is a precision-engineered ring set designed for high-performance eight-cylinder engine builds and complete overhauls. Built for mechanics and enthusiasts who demand accurate bore fit and consistent compression control, this performance-series ring kit addresses the critical need for proper blow-by sealing and oil control in both naturally aspirated and modified powerplants. File-fit construction means these rings require hand-fitting to your specific bore for optimal clearance and function—a hallmark of premium ring quality that separates quality rebuilds from rushed work.

Each ring in this set features a 1.0mm top compression ring, 1.0mm second compression ring, and 2.0mm oil control ring configuration optimized for standard tension performance across typical 8-cylinder applications. The steel construction with HV385 thermal treatment provides superior hardness and heat resistance, ensuring the rings maintain proper sealing geometry even under sustained high RPM and elevated combustion temperatures. The combination of file-fit tolerances and HV385 hardening delivers the ring stability needed for cylinder pressure retention without excessive drag, resulting in improved efficiency and reduced oil consumption in rebuilt engines.

This ring set is ideal for engine builders and serious DIY mechanics performing complete rebuilds on 4.275-inch bore engines, including many classic muscle cars, truck platforms, and performance conversions. Proper bore measurement and file-fitting during installation is essential—take time to measure your bore accurately and hand-fit each ring to achieve the manufacturer's recommended side clearance and end gap specifications. Whether you're restoring an original engine or building a high-revving stroker, these performance-series rings deliver the seal integrity and durability required for reliable, long-term operation.