Clevite MS-2218HX Main Bearings Sets Various forms of main bearing grooving have been used over the years. We are frequently asked what difference grooving makes. First, its essential to understand that bearings depend on a film of oil to keep them separated from the shaft surface. This oil film is developed by shaft rotation, as the shaft rotates it pulls oil into the loaded area of the bearing and rides up on this film much like a tire hydroplaning on wet pavement. Grooving in a bearing acts like tread in a tire to break up the oil film. While you want your tires to grip the road, you don't want your bearings to grip the shaft. The primary reason for having any grooving in a main bearing is to provide oil to the connecting rods. Without rod bearings to feed, a simple oil hole would be sufficient to lubricate a main bearing. Many early engines used full grooved bearings and some even used multiple grooves. As engine and bearing technology developed, bearing grooving was removed from modern lower main bearings. The result is in a thicker film of oil for the shaft to ride on. This provides a greater safety margin and improved bearing life. Upper main shells, which see lower loads than the lowers, have retained a groove to supply the connecting rods with oil.

**Requires Thrust Washer Set, not included.
Use With Part Number TW-610S, Material Grade High Performance, Series H Series (Tri-Metal), Size Standard, Suffix X - .001in Extra Oil Clearance
Main Bearing
Full Sets Only