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Discussion Starter #1
I'm rebuilding my turbo LT4 (Gen II) after only 500 miles because the tuner ruined the the rings. I'm putting in a new valvetrain and pistons, but am using the same crank and rods since they only have ~500 miles on them.

Since most of the basics are the same, I'm referencing the build sheet from Tom Masek. He used a -.001 size bearing only on the bottom for both the main and rod bearings. I'm looking at the Clevite coated H series bearings (CB-663HNK + CB-663HNK-1 and MS-909HK + MS-909HK-1) Is this something that's done when getting very specific for oil clearance? Is this pretty commonly done? I just want to make sure since I obviously need to by two sets of each ring set since they don't sell just tops and bottoms.

Thanks in advance!
 

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Discussion Starter #5
Yep. Common to get the clearances where you want em.
Thank you. I only want to do this once (again), so if that's what it takes, 4 sets of bearings! I guess I'll try to find someone that needs the opposite sides! haha

Okay, glad I asked. My builder happened to both sets of the -.001 size on the bottom. He didn't specify why though (and now he's retired. :/)
 

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It doesn't really matter on the rods but if you half shell the mains keep them the same, all uppers or all lowers.
 

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Discussion Starter #7
It doesn't really matter on the rods but if you half shell the mains keep them the same, all uppers or all lowers.
Hmm, that would save me some cash only doing the mains for sure.

Are you saying just to ensure I do the -.001 on all of the uppers or the lowers, not a lower some and uppers on the others? Just making sure I interpreted that correctly.
 

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Hmm, that would save me some cash only doing the mains for sure.

Are you saying just to ensure I do the -.001 on all of the uppers or the lowers, not a lower some and uppers on the others? Just making sure I interpreted that correctly.
Yes, If you "half shell" main bearings you buy two sets. Use all the lowers of one set and all the uppers of the other set. In the end you will have a "half shelled" set on the shelf.
 

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Hmm, that would save me some cash only doing the mains for sure.

Are you saying just to ensure I do the -.001 on all of the uppers or the lowers, not a lower some and uppers on the others? Just making sure I interpreted that correctly.
The rods may need to be half shelled depending on the actual clearances, however as they do not have to honor bore alignment like the main bores. You could theoretically have them half shelled randomly. I am way too OCD to do this but it could be done and not hurt anything. I have to half shell a lot of engines and it seems the coated bearings may be a contributing factor but I really like the Calico coated ACLs so I do whatever is necessary to get the clearance where I want it. This can vary from mfg to mfg as there is some room in the industry standard tolerance and it just depends on which end of the range you're on as to what needs to be done to work it out.
 

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I've always put the X clearance bearing on the cap since the crank tries to push down. I don't think it matters all that much tho honestly especially on the rods.
 

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I asked this question years ago and was told it didn't matter. So I bought 1 set of X bearings and used the top half on one and the bottom half on another to save on buying so many
 
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