Help With Main Bearing Clearance Issue.
07-10-2011, 06:19 PM
#1
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Help With Main Bearing Clearance Issue. Hello guys, I'm in the process of building my 98 ls1 and came into a problem. My bearing clearance as you can see below is way to loose ranging from .0035" - .0040". My question is if possible, what size bearings will I need to tighten up the clearance by .002".
Main Bearing
Housing Bore
1) 2.7524
2) 2.7524
3) 2.7524
4) 2.7524
5) 2.7524
Main Bearing
Journal Diameter
1) 2.5586
2) 2.5589
3) 2.5589
4) 2.5584
5) 2.5587
Difference
1) 0.1938
2) 0.1935
3) 0.1935
4) 0.1940
5) 0.1937
Main Bearing
Thickness
1) 0.1900
2) 0.1900
3) 0.1900
4) 0.1900
5) 0.1900
Main Bearing
Clearance
1) 0.0038
2) 0.0035
3) 0.0035
4) 0.0040
5) 0.0037
Main Bearing
Housing Bore
1) 2.7524
2) 2.7524
3) 2.7524
4) 2.7524
5) 2.7524
Main Bearing
Journal Diameter
1) 2.5586
2) 2.5589
3) 2.5589
4) 2.5584
5) 2.5587
Difference
1) 0.1938
2) 0.1935
3) 0.1935
4) 0.1940
5) 0.1937
Main Bearing
Thickness
1) 0.1900
2) 0.1900
3) 0.1900
4) 0.1900
5) 0.1900
Main Bearing
Clearance
1) 0.0038
2) 0.0035
3) 0.0035
4) 0.0040
5) 0.0037
07-10-2011, 08:28 PM
#3
How are you measuring? The only way to get a correct clearance is to install the bearings, torque the caps to spec, and measure the ID. From this number, subtract the individual crank pin OD. I'm not seeing this in your calc's, and it appears your not taking the bearing "crush" into account...
07-10-2011, 10:01 PM
#4
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I't was measured by installing the bearings, installing and torquing mains to spec, setting the dial bore gauge to the crank journal diameter and then measuring.
What I was attempting to ask was, is their a manufacturer that sells main bearings which tightens up the clearance by .002". I have found only ones that tighten it up by .001", but this is still to loose and will give a clearance of .0025" - .003". Im trying to get it in the .0015" - .0020" range.
What I was attempting to ask was, is their a manufacturer that sells main bearings which tightens up the clearance by .002". I have found only ones that tighten it up by .001", but this is still to loose and will give a clearance of .0025" - .003". Im trying to get it in the .0015" - .0020" range.
07-10-2011, 10:21 PM
#6
Mine are set up .002- .0025. Measured with the red plastic gauge, yes bearing companies make different bearing thinkness. I ran clevite bearings, u can call them and talk to them on the phone and tell them you .002 tigher bearing. .0015 is even tight for gm factory specs
07-10-2011, 10:43 PM
#7
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Hopefully they make them for LS engines, for gen 1's they have them from .001"-.005" then .010, etc. If not the engine is off to the machine shop to get the main caps cut and bored/honed back out to spec.
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07-11-2011, 03:44 PM
#10
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Found the problem, because the main caps are tight against the side of the block a very very small amount of material is removed and gets stuck increasing the clearance. I fixed the problem and no getting .0025" of main bearing clearance.
