420A 420a worn crank?

[DrewmHolland]

I'm rebuilding my motor after spinning 2 bearings on cylinders 1 and 4. The journals look fine and pretty smooth since it never ate through the aluminum shell on the bearings. Is there a way to check if my crank is within spec, and how much play is allowed before it causes a problem?

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[BLACK'98DSM]

You need a micrometer to measure the diameter of your crank journals. Looking smooth does not mean they're fine. Could just be evenly worn.

Even after verifying the crank is within spec, I would use some plastigauge when installing the new rod bearings the check your clearances.

 

[97egl]

If the bearings actually "spun" where they turned inside the rod the rods also need to be checked or just replaced. Since they are cracked powdered metal rods they cannot be reconditioned without using larger OD bearings which are not usually readily available. If the bearings actually spun it is almost certian the rods will not be usable as they are.

 

[DrewmHolland]

I went ahead and used a plastigage and everything read about 0.0015-0.0020 so i'm happy, but yes the rods have been ruined and I already have replacements so everything is good.