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Fitting engine bearings

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Do all bearings require the bearing tang. I have just noticed on a block i have received back from the machinist that had a tunnel alignment that the main bearings do not have a tang. I have never noticed this before and thought it to be standard to stop the bearings rotating.

Mazda 3 MPS L3 Engine

Thos little tangs on the bearing shells actually don't stop the bearings from rotating - that's a common myth. the crush on the bearing shells is what prevents them rotating and the tang is purely there for location purposes. With that in mind it's not essential although I don't recall ever using a set of bearings that didn't have a locating tang.

The main bearings are held in with a single cradle (not caps) on those engines and don't have locating tangs, but the connecting rods do.

The problem that I am facing is, since there are 2 bearing halves, how do you ensure that the bearings are centered in the bores?

The cradle doesn't have dowels and has no visible marking/alignment in the block (parting lines aren't flush).

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