Perf. Piston Ring Set V8 4.140 Bore 1.2x1.5x3.0

The Perf. Piston Ring Set V8 4.140 Bore 1.2x1.5x3.0 is the OEM-grade solution for restoring or upgrading performance in big-block and small-block V8 engines with a 4.140-inch bore diameter. Whether you're rebuilding a tired engine, performing a top-end refresh, or installing oversized pistons, this NPR ring set maintains proper compression, oil control, and blowby sealing. Mechanics and engine builders rely on NPR piston rings for their dimensional accuracy and consistent performance across thousands of miles of street and strip duty.

This ring set features a three-piece design with 1.2mm top ring, 1.5mm second ring, and 3.0mm oil control ring geometry engineered to handle modern fuel octane ratings and extended oil drain intervals. The specified ring thicknesses optimize the critical balance between gas sealing efficiency and minimal friction, allowing the piston to move freely within the bore while preventing compression leakage and controlling crankcase oil vapor. NPR's precision manufacturing ensures consistent gap clearance and radial pressure across the ring package, reducing cold-start wear and extending engine longevity on rebuilt long-blocks.

This ring set is essential for any 4.140-bore V8 engine rebuild—from muscle car restorations and vintage hot rods to modern LS and traditional big-block conversions. Before installation, confirm your piston dome design, ring groove dimensions, and end-gap requirements with your engine builder or machine shop; proper ring gap (typically 0.004–0.006 inches per ring) is critical for reliable performance. Stock this NPR set for emergency rebuilds or routine maintenance, and always pair it with fresh pistons and properly honed cylinder walls for best results.