MAHLE CB-743HN-19 H-Series Connecting Rod Bearing Pair Big Block Chevy 0.019" Undersize

The MAHLE CB-743HN-19 is a Clevite H-Series connecting rod bearing designed for Chevrolet Big Block V8 engines displacing 348, 366, 396, 402, 409, 427, 454, and 496 cubic inches. This bearing is sized 0.019" undersize, making it the correct choice for engines with reground crankshaft journals turned to that specification. Sold as a pair (one upper and one lower half-shell).

H-Series Performance Design:

• Developed for NASCAR-type racing but engineered for all types of competition and performance engines
• Medium eccentricity profile for optimal oil film distribution across the bearing surface
• High crush factor ensures precise retention and seating within the connecting rod bore
• Hardened steel back with unplated surface for superior dimensional accuracy and housing bore contact
• Thin overlay constructed from a copper-lead alloy with an electroplated babbitt surface to reduce drag and resist flaking under high loads
• Enlarged chamfers provide additional crankshaft fillet clearance, critical for performance-ground crankshafts
• No flash plating — bearings seat more accurately and consistently without the interference of a sacrificial flash layer
• Precision wall tolerance of +/- 0.00015 in. for consistent oil clearance and reliable performance
• Cast copper-lead construction yields approximately 20% greater fatigue strength compared to sintered (powdered metal) alternatives
• Narrowed width for use in performance applications requiring additional fillet clearance

Clevite H-Series bearings are recommended when crankshafts have oversize fillets and where the engine operates in the medium-to-high RPM range. They should also be selected when contact patterns produced by P-Series bearings are too narrow — ideal contact patterns cover two-thirds to three-quarters of the bearing surface. The CB-743HN-19 is the trusted choice of engine builders for Big Block Chevy street performance, circle track, and endurance racing applications.