Bearing Groove ? Full or half?

[MidShipCivic]

In the ACL catalog it states two different types of main bearing for early 6 bolts half and full grooved? Whats the deal with that ? Which one do I select?

 

[Big Woo]

The upper main bearing halves, have grooves to promote oiling into the crankshaft main journal oil holes to subsequently provide lubrication to the connecting rod bearings. Fully grooved main bearings allow this to happen for 360 degrees of crankshaft rotation. However since the stock Mitsubishi crankshafts are cross-drilled, this means that you do not need a fully grooved main bearing to get 360 degree positive oil feed into the crank mains.