Enginetech M41258-STD Moly Piston Ring Set GM 348 364 400 402 425 Standard Bore

The Enginetech M41258-STD is a full moly piston ring set designed for GM and Chevrolet W-series V8 engines displacing 348, 364, 400, 402, and 425 cubic inches. This standard bore (STD) set is a direct drop-in fitment for engines with a 4.125-inch bore diameter, covering applications from 1958 through 1980.

Ring Set Specifications:

• Bore Size: 4.125 inches (Standard)
• Top Ring Thickness: 5/64 in.
• Second Ring Thickness: 5/64 in.
• Oil Ring Thickness: 3/16 in.
• Drop-In Fit — no file fitting required
• Ring Type: Plasma Moly face coating for superior wear resistance
• Sold as a complete set

Enginetech Ring Quality:

• Produced in OE manufacturing facilities to meet or exceed original equipment specifications
• Compression rings manufactured from high-quality gray iron, ductile iron, and high-strength steel
• Multiple face designs available including barrel face, taper face, positive twist, reverse twist, and Napier face configurations
• Oil ring assemblies feature engineer-designed expanders to prevent overlap during installation

This Enginetech moly piston ring set is a reliable choice for engine rebuilders restoring classic GM big-block W-series engines. The plasma moly coating provides excellent heat resistance and reduced friction, helping to extend engine life and maintain proper compression and oil control throughout the rebuild.