Re: More crank bearings

Posted by scott#2 on January 12, 2005 at 08:32:14 from (138.88.166.64):

In Reply to: Re: More crank bearings posted by CNKS on January 12, 2005 at 07:15:08:

CNKS,

I dont know much about tractors but I know about precision engines. Plastigage is primarily used for checking the grind job and bearing quality, to insure a accurate bearing oil clearance. I have had cranks come back that would not give a consistant reading across the journal. (bad dressing job on crank machine wheel) There are just too many variables in using plastigage on old/used parts to get a ballpark figure, especially since the ballbark is quite small when it comes to oil clearance. Block bores, rod bores, bearing quality (from different manufactures), bearings worn uneven, out of roundness, crush factors torque values, cleanliness on and on and on. I have even used different manufacturers bearings on the same engine when setting the bottom end up and often get different results. Plastigage is such an accurate way of measuring clearances that there is absolutly no room for variables or mistakes. Drop an eyelash anywhere in there and the reading is flawed. Dryer lint, cigarette ash, any contamination will give false readings. All readings should be taken with dry clean surfaces. This means block bores, main bearings (both sides), rod bores and their inserts (both sides). No oil, no nothing anywhere. If a journal is out of round or just round and worn to a smaller diameter, no amount of torque will push it down into the bearing for an accurate measurement. You only ues assembly lube (moly) on final assembly.

Hope this helps,

scott#2

Follow Ups:

• Re: More crank bearings CNKS 09:42:02 01/12/05 (0)

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