minimum bearing clearances

I had the same problem with coated bearings. SoCal diesel line honed the bearings flans got them where they needed to be.
 
If he won't replace the bearings, and he 'sized' everything, get him to grind the journals to the correct dimension for proper clearance. The fact that you have .002" from max to min worries me though. Is it the bearings or the journals that are different sizes?
 
I'll have to take some measurements..he told me to swap tops around till I got a measurement that was pretty close..he says he does it with everyone of his builds..it takes time but sometimes that's what it takes he told me..he said it sounds like I have two thicker bearings on #5 and 2 skinnier ones on #1 bearing..so I'll swap those around measure it again and see where we're at..I'm going to also clean everything again with lint free towels..after talking to a guy today I found out the red towels from autozone aren't the best option when assembling a motor..so we'll see,what we are,after a good cleaning and bearing swap..

Looking at summit they have min.0017 max .0047 on the cummins bearing page..just a little tidbit I found tonight while searching google till my eyes wanted to fall out..
 
Took some measurements of bearings.
NEW set of main bearings uncoated came in at .098
My coated bearings came in at .097

NEW set of rod bearings came in at .079
My coated bearings came in at .078

So unless he line honed everything then coated them I dunno what's going on..I did however find a good amount of coating on the back side of the #5 bearing.the spot that had the extra coating splatter came in at .099 so that could be part of my problem..I didn't really look at back side I just wiped everything down and installed..
Would also like to add all measuring was done with calipers because I do not own a set of mics,its not proper I'm sure but it's all I have at this point..
 
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Calipers are no good (as you know). Get a bore gauge if nothing else, although I'll take an inside mic over anything for doing that. But check with plasitgage with the new bearings and see if the numbers jive with what you recorded.
 
Where in the bearing would I take measurements with Mic?inside, outside, middle?
 
Top to bottom, and Cummins recommends 45 degrees on either side. I prefer going closer to the split in the cap, as if the fit is off between the block and cap, those are the numbers that will tell you. You'll have to go front and rear measurements due to the oil groove in the upper shell.
 

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Tate said:
Top to bottom, and Cummins recommends 45 degrees on either side. I prefer going closer to the split in the cap, as if the fit is off between the block and cap, those are the numbers that will tell you. You'll have to go front and rear measurements due to the oil groove in the upper shell.
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I believe he means he is using calipers to measure the thickness of the bearing, vs an outside mic. I sure hope nobody would attempt to check engine clearances like that. LOL

I'd say to put the new bearings in and plastigauge them. If you still have the same measurements in the same places, I'd start looking at the quality of the machine work.
 
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If you're gonna build engines, this would be a good investment.
 
TheBigNasty said:
I believe he means he is using calipers to measure the thickness of the bearing, vs an outside mic. I sure hope nobody would attempt to check engine clearances like that. LOL

I'd say to put the new bearings in and plastigauge them. If you still have the same measurements in the same places, I'd start looking at the quality of the machine work.
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Yes I was just using calipers to measure thickness of bearings..I would never do that to check clearances..I was just looking to get a rough idea..I had bearing supplier measure same bearings to give me an idea of it was the bearings that were noticably different..now that I know they are not to far off in that sense I'll pull it all apart and clean and check it all again..and recheck..if it's still off I'll order new bearings..after finding coating on backside of #5.wouldn't be surprised if there's more coating or other foreign material in/under bearings..I'll start fresh and see what I have.

Thanks a bunch for all the help I'll be keeping thread up to date with what I find.
 
Looking at the numbers from my current build, the shells are all .0970-.0972 thick. So yours seems to be in the ballpark. Be nice to know what the journals as well as the mains w/o bearings installed measure.
 
Snap gauges, yes. Calipers can get you close, although measuring a 3.25" journal with them will be tricky since the jaws are not likely long enough. You should be able to get a cheap set of mics pretty affordably.
 
Sorry I should've specified.I meant to find inside diameter..yeah I've found a few sets.none of which come with the 3-4" Mic.but that one alone is only around 50 bucks..
Instead of plastigauge could I not install bearings inside main caps,torque down.measure inside and then measure crank journals and do some math? Same with rods??or would plastigauge be a better option.
 
Tate said:
Looking at the numbers from my current build, the shells are all .0970-.0972 thick. So yours seems to be in the ballpark. Be nice to know what the journals as well as the mains w/o bearings installed measure.
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You talking about just torquing mains to block and taking a measurement? I can do that with a straight edge and snap gauges I think.
 
rjustman said:
Sorry I should've specified.I meant to find inside diameter..yeah I've found a few sets.none of which come with the 3-4" Mic.but that one alone is only around 50 bucks..
Instead of plastigauge could I not install bearings inside main caps,torque down.measure inside and then measure crank journals and do some math? Same with rods??or would plastigauge be a better option.
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You should be doing both. That way you actually know whats in or out of spec. You should have at least three diameters on each bearing, 6 would be better (front and rear). 2 on each journal, but 4 would be better. Then plastigage. Plastigage is there to confirm your micrometer measurements.


rjustman said:
You talking about just torquing mains to block and taking a measurement? I can do that with a straight edge and snap gauges I think.
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Thats what I was referring to. Its not really required, but I was doing that since I upgraded to 14mm studs and my mains were out of round and was easier than installing the bearings to check and possibly damage them. Its one more piece of info you can have.
 
rjustman said:
Sorry I should've specified.I meant to find inside diameter..yeah I've found a few sets.none of which come with the 3-4" Mic.but that one alone is only around 50 bucks..
Instead of plastigauge could I not install bearings inside main caps,torque down.measure inside and then measure crank journals and do some math? Same with rods??or would plastigauge be a better option.
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http://m.ebay.com/itm/0-6-Outside-Micrometer-Mic-Set-0-0001-Precision-Machinist-Carbide-Instrument-/311050049438?nav=SEARCH
 
I actually bought that set and checked them against our starrett mics. They were within 0-.001 of them.
 
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