.010 under Size Performance HP Series Rod and Main Bearings Compatible with Chevy SBC 327 Large Journal, 305 & 350 Engines. These HP-Series rod bearings were developed mainly for drag race applications needing a material harder than the Babbitt top layer. These applications demanded a structure that could withstand high loads for short durations and still offer higher embeddability and compatibility. HP-Series main bearings are recommended for street and strip performance applications. They're designed for blown, turbocharged, NOS, and alcohol-fueled engines using aftermarket crankshafts. These main bearings have greater eccentricity for superior oiling at high rpm, and a chamfered surface for large radii crankshafts. HP-Series bearings also feature large, chamfered oil holes—and are available in 1/2 grooving for improved oiling to withstand high-rpm applications. Order the bearings designed for fitment with your specific engine.