M20 Bearing Differences

How To Identify An Early Or Late M20 Block

Ordering our M20 Stroker Kit or ACL Race main bearings? Identifying your M20 block as early or late is straightforward once you know where to look.

Start With The Model Year

As a general guide, M20 engines from 1987 and earlier are considered early, while 1988 and later are considered late. Model year is a useful starting point, but it isn't proof. These cars have been on the road for roughly four decades, and blocks or complete engines may have been swapped along the way.

Check The Main Bearing Cap

To confirm what you have, remove a crankshaft main bearing cap and inspect the tang notches along one edge.

  • Early M20 main bearing caps have one tang notch
  • Late M20 main bearing caps have two tang notches

The photo below shows the difference between the two variants.

Photo showing the difference between early and late model BMW M20 crankshaft main bearings. Created by BimmerHeads.

Still Unsure?

If you're still not sure what you're looking at, contact us before ordering. Send us a clear photo of the main bearing cap and we'll help confirm what you're working with.