Perfect Circle MS1038H H-Series Main Bearing Set Small Block Chevy 400

The Perfect Circle MS1038H is a high-performance main bearing set designed for Small Block Chevrolet 400 cubic inch V8 engines (1970-1980). This H-Series bearing set features advanced tri-metal construction with a hardened steel backing and carefully selected overlay material for superior durability in demanding applications.

Key Features:

• H-Series performance design with medium eccentricity and high crush for optimal heat transfer
• Tri-metal (TM-77) construction with hardened steel back and thin overlay
• Half-groove design (1/2 groove in upper bearing) for improved lubrication
• Enlarged chamfers for greater crankshaft fillet clearance
• Manufactured without flash plating for better initial seating
• Ideal for medium-to-high RPM performance and racing applications

Originally developed for NASCAR competition engines, H-Series bearings are engineered to handle the demands of high-performance builds. The high crush factor ensures excellent heat transfer and resistance to bearing rotation under extreme conditions, while the medium eccentricity helps minimize housing bore deflection. These bearings are specifically designed for crankshafts with oversize fillets and engines operating in the medium to high RPM range.