[cobalt327]

This is not caused by the 'coating' on the bearings.

[4 Jaw Chuck]

Its not through the coating/plating, if you can't catch a fingernail its a "lint/dust" scuff....looks pretty minor from my chair.

[cobalt327]

#1 looks OK. #5 doesn't look bad. That there's such a difference between the bearing on the left and the others points to an irregularity that I would be looking into. Might have been nothing more than an oil passage loaded up w/grit to that bearing- but I won't call it "normal". YMMV.

[Dougie]

Question,

If the bearings have a spray on coating that isn't precision applied, wouldn't that cause inaccurate readings when checking the size using either a micrometer or plastigage?

[mouse77]

Originally Posted by Dougie

Question,

If the bearings have a spray on coating that isn't precision applied, wouldn't that cause inaccurate readings when checking the size using either a micrometer or plastigage?

Yes..... thats why competition bearings have no coating. As for plastiguage, youre mashing plastercene and measuring it, by eye, off of a printed stripe on paper. Great for a rough idea, but not very precision. It also doesnt tell you if your bearing crush is off and the parting lines are wide or if the mains have been ovaled.
"most" engine builders, besides for the armchair engineers here, lightly (with grey, "very fine") scotchbrite the coating off before using a bore gauge to determine clearance when using cheapie bearings. Its a startup coating and if you use any assembley lube it really isnt needed.

And the funny part is, unless you have 10 sets of + and - .001 and std fit bearings to match the under/oversize bore to bore and a crank polisher on hand, measuring anything besides the basic .010 etc, wont do much other than allow you to tell someone your clearance on a web forum.

YES, this fellow may had have a little trash in the crank oil holes he missed, or maybe the cam bearings were left in before hot tanking and some gunk was in the grooves, or maybe driving in the new cam bearings knocked some casting sand out of a crevice, but like most people said, he has nothing to worry about.

And im going to go out on a sturdy limb and say that "damage" was caused either by rolling it over by hand, or an extended cranking time, no fuel, dead battery etc.
Because as im sure everyone knows on here , the crank doesnt actually ride on the bearing when it has oil pressure, it rides on the oil "sheer" created by the oil pressure in combination with the clearances. Your crank actually floats in the mains on oil. Pretty cool huh?
So there is no bearing to surface contact, unless the engine doesnt have a live oil supply.

[Torque454]

I think i'd stick it back together and run it. I've run engines with worse bearings than that with no problems. It may not be ideal but it works.

I think almost every used engine i've been into has had imperfectly worn bearings. Even quite a few with copper showing. Some are still running and driving. They aren't high performance engines or anything, and wouldn't be much of a loss if they did spin a bearing or something so i've just run them. Those bearings you show look pretty good to me compared to most bearings I see. May not be perfect, but I dont think any bearing will be perfect for very long anyways.

[cliff tate]

mouse is bang on if you ar building a engine to run nascar or a non claimer and hope to get all season out of 1. but i don't think to maney on this site are in that Erena. I worked for a cat dealer,we did a lot of engine work, 1 year we built 52 3208 cat truck and ind. engines.each one was assembled and clearance checked with plastigauge. not 1 failure.tho every engine was pre lubed then dynowed, 5min warm up full power for 30 min cool down 10 then to the customer.the moral hear is cleanliness senceable checks on assembly.we did find issues with plastigauge and send parts back to machine shop. clif