bearings size

[AlphaVision]

After the catastrophic bearing failure I am in the process of my 6-bolt engine rebuild. This time I want your advice on what bearings I should get (std or oversized). A friend of mine measured the crankshaft. Here's the data:

main journals:
1: 57.00 mm
2: 57.00 mm
3: 56.99 mm
4: 57.00 mm
5: 57.00 mm

i think those are the stock specs
56.9722 mm (2.24300 in)
0.00508 mm (0.0002 in) taper limit (what does that mean)
0.01524 mm (0.0006 in) out of round (is this the roundness of the journal or the tunnel)

rod journals:
1: 44.99 mm
2: 44.99 mm
3: 44.99 mm
4: 44.99 mm

stock specs
44.9834 mm (1.77100 in)

So what is frustrating here is that the crankshaft has actually larger rod journals than stock Or this could be some unwashed oil film?

According to ACL catalog i am inside the specs
Min Std Shaft Size 2.2433in / 56.98mm
Max Std Shaft Size 2.2441in / 57mm

rod bearings
Min Std Shaft Size 1.7713in / 44.991mm
Max Std Shaft Size 1.7717in / 45mm

I think I need standard bearings, but what can you say to me?

 

[donniekak]

What tool did your friend use to measure the journals? This isn't the same crank out of the failed engine, is it?

 

[AlphaVision]

I am not sure. He had to borrow a special micrometer from a professional, because he only had a regular one like this.

The crank is a fresh one, taken from a running 108K miles block.

 

[talonDSMerr]

Taper is if the journal has a different (larger/smaller) diameter when you take a measurement at another point on the journal. Out of round is the roundness of the journal being more of an oval than a true circle.

If you are within ACL's specs for the standard size bearings, you should get the standard size bearings. Make sure the micrometer your friend was using is accurate enough, down to .0001" or .002mm. Check with him and have him measure it again with a more accurate micrometer if need be.