Clevite MS-909H-20 High Performance Main Bearing Set

The Clevite MS-909H-20 is a high-performance main bearing set designed for demanding racing and performance engine applications. This H-Series bearing features optimized 180-degree upper shell grooving that maximizes oil film thickness while providing adequate oil supply to connecting rod bearings.

H-Series Performance Features:

• Medium eccentricity design for optimal contact patterns covering 2/3 to 3/4 of bearing surface
• High crush construction ensures maximum bearing retention in performance applications
• Hardened steel backing provides exceptional strength and resistance to fretting
• Thin overlay design prevents overlay fatigue and hen tracking in high-load conditions
• Enlarged chamfers accommodate oversize crankshaft fillets common in performance cranks
• No flash plating for improved bearing seating and bedding characteristics
• TriMetal construction delivers superior durability and load capacity

Technical Design:

The 180-degree upper shell grooving represents the optimal balance between oil delivery and bearing performance. This design maintains maximum oil film thickness on the loaded lower bearing shell while the grooved upper shell supplies oil to the connecting rods. Extended grooving patterns actually reduce bearing performance by breaking up the critical oil film that separates the bearing from the shaft surface.

Applications:

H-Series bearings are ideal for NASCAR-type racing, road racing, circle track, and high-RPM street performance engines. Use this bearing set when your application requires oversize fillet clearance, medium to high RPM operation, or when P-Series bearings produce contact patterns that are too narrow. If you're unsure which performance bearing series to choose, H-Series represents the best starting point for most performance applications.

The MS-909H-20 features 0.020" undersize dimensions for use with crankshafts that have been ground 0.020" undersize on the main journals.