ACL race main bearings for NA/NB

Main bearings for 1990-05 Miata engines. These are quality ACL race bearings for maximum strength inside maximum horsepower engines.

Available in stock, 0.25mm (0.010") or 0.50mm (0.020") oversize. They also come in 0.025mm (0.001") oversize.*

Included in our engine rebuild kits.

Crank measurements in mm and inches:

• Stock = 49.938-49.956 / 1.9661-1.9667
• .25 / .01 = 49.704-49.708 / 1.9569-1.9570
• .50 / .02 = 49.454-49.458 / 1.9470-1.9471

Please note that we can't accept returns on bearings that have been removed from the plastic wrap.

*0.50mm & 0.025mm sizes are unavailable until further notice.