White metal bearings

[Vintageben]

Hi everyone and thanks in advance for any help. I have a 1929 Chrysler that has been sitting for a long time    and I'm checking the engine over, giving it a good clean and new piston rings. Any way the question is the big end bearing look fair but are very dull in colour (grey) I know when these are new they are a nice shiny silver colour should I be polishing these some how? If so what with. I seem to recal someone telling me motors that have sat a long time tend to run bearings because of this tarnish. Any way any help appreciated.

[Taylormade]

Any cracks in the metal?  These bearings can fatigue with old age.  I'm no expert, but I know this type of bearing can be scraped - it was done in the old days, but I don't know the correct technique.  Someone who has dealt with this problem will chime in soon, I'm sure.

[Vintageben]

Surprisingly no cracks that's why I don't want to risk the bearings at this stage

[cahartley]

Leave them alone.

Do not remove 1 molecule of Babbitt if you don't have to.

That's what good fitting babbitt bearings look like after they have run for a while.

Shim if necessary.

[Bloo]

Regarding scraping, that is done to make the bearing fit, not because the bearing looks funny. There were scraper tools for this. You put dykem blue on the surface and turn the crank over, then you take it apart and scrape down the shiny spots a little. Continue until you have an acceptable ammount of contact area (75%?), then re-shim the bearing to the correct clearance.

 

Scraping doesn't sound like what you need. Not yet anyway.

 

2 hours ago, cahartley said:

Do not remove 1 molecule of Babbitt if you don't have to.

 

This^^

Edited August 22, 2017 by Bloo
.. (see edit history)

[Bhigdog]

Since it's apart you might want to check the bearing clearance with plasti-gage.......................Bob

[c49er]

Measure the clearances carefully and accurately...if good and in spec and the bearings look good.. use them.

Cleanliness is a absolute must!

Grey is OK.... copper.? pitting and voids..... no no

Edited August 22, 2017 by c49er (see edit history)

[robert b]

Ben  do not touch them at all ,more info ring on the moible phone and will have chat with you . B ob

[Vintageben]

Thanks Bob will give you a call when I get ten yeah it's pretty safe that I won't touch it too much other work at the moment. Thanks everyone else for there comments

[Restorer32]

Have a customer who was amazed that we use plasti-gage to measure bearing clearances. He had never seen anything like it and couldn't believe that it could be accurate,

[Vintageben]

Yeah I have had good success with

plastigage on other engines and surprised a few friends with it too

[Stude Light]

Plastigage is great stuff and easy to use. This is a photo of the plastigage after being compressed on a bearing cap and comparing the results to the gauge provided. I think this was on a connecting rod cap.  Personally, I clean everything until spotless (no lint either). I then apply an extremely light oil (something like sewing machine oil) to the crank to keep from scoring bearings if parts get accidently rotated. Applying a regular engine oil will take up some of the gap you want to measure.  I lay the plastigage in place on the crank and bolt up a dry cap. The plastigage will stick to the non-oiled surface of the cap. Solvent clean when done. This is just for measurement and shim adjustment....use a good assembly lube upon final assembly. Note the fairly dull gray color of the used bearing - normal.

[herm111]

We use 30W oil on shaft and Cap. If you don't use oil, the Plastigage will not spread out to its fullest capability. If you don't use oil on the cap where the Babbitt is, there is a large percent that it will sink into the Babbitt and leave an imprint.

 

For clearance we set at .001-00 per inch, Plus .000-50 thousandths.

 

A 2" crank then would have .002-50 thousandths, as a 6" crank would have .006-50 thousandths clearance.

 

Never measure the Plastigage in the cap, always measure the plastigage that is on the crank.

 

The reason being is the crank is hard and the Plastigage will never sink in, unlike Babbitt.

[Larry Schramm]

Nice tolerances.

[Stude Light]

I measured both ways (my method and also as herm111 posted) and got the same results.  I figured having regular engine oil in the space it would take up some of the clearance but I guess not.  Considering Kohnke Rebabbitting does this for a living, I would defer you to his methodology as the correct procedure - he is the expert in this area.  Regardless, the plastigage procedure isn't that hard to do. That machined new Babbitt looks really nice but used dull gray bearings are fine as long as everything is round and clearances are properly set. Good luck.

 

 

Edited September 13, 2017 by Stude Light (see edit history)