"New" crankshaft: how to measure the mark of STD bearing?

[Korg77]

guys, i need to replace the crankshaft, so i bought an used one, but w/o scratches. I don't know the mileage of donor's engine, so i afraid it won't be enough to just calculate a marks of bearings using the digits on the block, rods and crankshaft.

The only instruments i have allow to measure up to 0,01mm (sorry for metric system), and whats about bearings - i need up to 0,001

Whats anther way?

 

[airbats801]

could buy some std bearings and do the ol plastigauge method and see if anything is out of spec. Thats the only way without some micrometers that you will be finding the clearance

 

[Korg77]

airbats801:
I have heard something about this. Where can i read more bout this method?

 

[airbats801]

just go to your local parts stopre and ask for .001 to .003 plastigauge

clean your crank journals up nice and good, and toss some std bearings in and put some plastigauge on the crank in a few areas on each journal. Assemble to spec then disassemble and see what the results are. there are markings on the package to tell you the results. Use some degreaser like zep to clean the bearings of the plastigauge.

 

[Korg77]

thanx very much!
Found this items in online shop.

 

[annoyingrob]

You can assemble it with your current bearings, see how it needs to be adjusted with plastigauge, and re-size accordingly. This is how I did mine.

Don't forget to change your thrust washers

 

[Korg77]

but current bearings i supposed as any used bearings got thinner. As i understand when i use plastigauge i need new bearings

 

[annoyingrob]

but current bearings i supposed as any used bearings got thinner. As i understand when i use plastigauge i need new bearings

I don't know, 5 of my main bearings were the same size as they were supposed to be. The only two that weren't were visually worn.

 

[tte]

Best you take it to a experienced reputable shop and tell them to mic it and let you know what size bearings to buy.


Cheers,
Roy

 

[annoyingrob]

but would a shop cost less then buying (worst case) another set of bearings when you find out the first ones are not quite right? I would use the markings, get the bearings, plastigauge it all, then if any are out of spec, re-size those ones.

 

[steve_mk3]

While it might be more expensive to take it to a shop. But, you will be sure of the correct bearings size.

If you make a mistake( plastigage is not exact) you will have a spun bearing and a new rebuild. That would be most expensive

 

[Korg77]

annoyingrob:
I think you are right. I'll do this way