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Old 02-26-2008, 12:19 PM
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Need Bearing Clearance Help

On my LS1 motor, checking my main bearing clearances with a mic and dial-bore gauge, my main bearing clearances come out at 0.003/0.0035 and becuase of the variance (eg different readings for the same main cap bearing- depending on where the gauge sits) I decided to double check with plastigauge, which yields measurements of 0.002 (????)

1) I've heard that platigauge measures tight, but isn't this a little too much of a difference?

2) Assuming that my mic's measurements are more accurate, shouldn't the fact that my crank journal measurements are at factor spec (2.5590) mean that there wouldn't be a need to get oversized bearings (since factory clearances are 0.0007-0.00212)?

I ordered 0.001 oversized bearings but am worried (based on the plastigage measurements) that I may bring my clearances in too tight.

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Old 02-26-2008, 12:37 PM
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Factory main bearing claearances are allowed to start at 0.0007? Seems awful tight to me. But, I'm an amatuer, and havn't worked on an LS1.


Last edited by PatM; 02-26-2008 at 02:07 PM.
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Old 02-26-2008, 01:09 PM
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We sell a lot of rotators and blocks and we clearance everything out and our customers from time to time check our work with NEW plastigauge and from they have always told me plastigauge compared to my measurements is right on.

Plastigauge is pretty simple how it works as its just a peice of wax string and it has been around long them most people on the site LOL.

Make sure your using a good bore gauge to measure a bearing bore with a bearing installed as the bearings have eccentricity in the and a bore gauge with ridgid fingers does not work as we have proiven this to more engine builders with our Sunnen bore gauges.
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