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Discussion Starter · #1 ·
so there were were the Machine shop was done with the boring .. assembling was happening and then.. the main bearing holes were too big by .002 even though the crank is standard... I believe what i need is called an overbearing, .002 thicker than a standard for a CPL 594.. does anyone know any place that sells such a thing... thanks for any reply..
 

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Are you saying the bearing bores in the block are oversized?. Normally a machine shop will check those and line bore if needed when servicing a block.
Are they all the same?
 

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Discussion Starter · #3 ·
Are you saying the bearing bores in the block are oversized?. Normally a machine shop will check those and line bore if needed when servicing a block.
Are they all the same?
Yes it appears the Main Bearing bores are over sized.. although I don't have the original mains.. someone had just replaced the bearing and then scored a piston.. and as the machine shop is assembling the short block... he measures the bore with the caps on and the bearing in and says they are loose.. at between .005-.006 using his bore gauge.. but that confuses me... back in the day it wasn't uncommon to find over and underbores on an engine with the factory adjusting with over and underbore bearing.. ( usuall .001-.003).. but i called a cumming dealer with a guy who understood the overboreing issue, but he says he had never seen it in a 4bt or a 6bt... so here I am looking for an answer.. if the machinist is correct the block has an overbore.. provided the bearings are correct.. and that is an issue I'm starting to look at.. does cumming make different size main for the older 4BT.. if so it is possible the bearings are at fault as they have an incorrect crush circumference.. i simpley don't know enough and don't want to pay for a line bore unless that is the only answer.. so .. I don't have any answer.. just lots of questions.. what could cause this to look like an over bore: wrong bearings? ... I don't know.. any help you could give would be greatly appreciated.. thanks
 

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Discussion Starter · #4 ·
Are you saying the bearing bores in the block are oversized?. Normally a machine shop will check those and line bore if needed when servicing a block.
Are they all the same?
( just as a note : are you from the BlackDuck MN area? .. I know it well)
 

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There are a flock of us Blackducks, this one is from West Aus.
Found some reference to over bore on 4BT big ends in the rods, nothing on mains.
Ford used to do over sizes on their engines, when the line bore machines wore they just oversized the bores instead of closing the caps and re-boring. They did not mark the blocks to the best of my memory.
May pay to give Mahle a call, they list under and oversize bearings.
Good luck with getting it up and running.
Cheers Steve
 

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I looked up serial # 21252230 which is a CPL 0594. The main bearing kit is 3802010 which is exactly the same as all other 4bt's. You may want to contact member CrewCab59 who is a Cummins dealer. He may have some idea as to where to find what you're looking for.
 

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Discussion Starter · #7 ·
There are a flock of us Blackducks, this one is from West Aus.
Found some reference to over bore on 4BT big ends in the rods, nothing on mains.
Ford used to do over sizes on their engines, when the line bore machines wore they just oversized the bores instead of closing the caps and re-boring. They did not mark the blocks to the best of my memory.
May pay to give Mahle a call, they list under and oversize bearings.
Good luck with getting it up and running.
Cheers Steve
Thank You... So appearantly the guy was using the wrong torque spec and when he went to the correct one it closed that mysterious gape... but thank you for you help!
 

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Discussion Starter · #8 ·
There are a flock of us Blackducks, this one is from West Aus.
Found some reference to over bore on 4BT big ends in the rods, nothing on mains.
Ford used to do over sizes on their engines, when the line bore machines wore they just oversized the bores instead of closing the caps and re-boring. They did not mark the blocks to the best of my memory.
May pay to give Mahle a call, they list under and oversize bearings.
Good luck with getting it up and running.
Cheers Steve
Thanks Steve... after much consternation and worry .. the guy found he was using the wrong torque speck and when he used the correct one... the extra gap disappeared... Thank you for your help and info.. Crikey Mate... what a thing.. Pat
 

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Glad it is sorted. Think you had better give him a full list of the torques and clearances required so he does not get confused anymore.
Cheers Steve
 

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Glad you got this worked out. Not often we hear of the issue you were having. A change in torque can definitely take out a few thousandths.
 
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