I am building my first mod motor and I have a question about the main bearing clearance. Its a 99 cobra, stock crank, aluminum block and I am using clevite main bearings with a calico coating. my question is that with the coating the main bearing clearance is only .0015. I measured the new bearings and the coating added .0004" to each half, I didn't realize it would add that much. should I order a bearing with and extra .001 clearance or run it.
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main bearing question
- Thread starter trent1000rr
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I am building my first mod motor and I have a question about the main bearing clearance. Its a 99 cobra, stock crank, aluminum block and I am using clevite main bearings with a calico coating. my question is that with the coating the main bearing clearance is only .0015. I measured the new bearings and the coating added .0004" to each half, I didn't realize it would add that much. should I order a bearing with and extra .001 clearance or run it.
That is the stock spec (.0015) But how did you measure the clearance between the crank and the block/caps?
-Mark
mic and a dial bore gauge.
That is the stock spec (.0015) But how did you measure the clearance between the crank and the block/caps?
-Mark
mic and dial bore gauge. It just seems a little tight to me but I have a couple friends that run ls engines that say they wouldn't worry about .0015" with the aluminum block.
Well for what it's worth, I have a iron block and my clearance was .00155. When I puled the motor to swap heads I removed the caps to check the bearing surfaces and no signs of oil starvation. Since it is a relatively small clearance you could have the crank polished. That should open it up .00005 to be on the safe side. Just remember this tight of a tolerance will need a thinner oil (i.e. the standard 5w30).
-Mark
-Mark
Well for what it's worth, I have a iron block and my clearance was .00155. When I puled the motor to swap heads I removed the caps to check the bearing surfaces and no signs of oil starvation. Since it is a relatively small clearance you could have the crank polished. That should open it up .00005 to be on the safe side. Just remember this tight of a tolerance will need a thinner oil (i.e. the standard 5w30).
-Mark
Ok. I will probably pay close attention to break in and run it.
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