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Discussion Starter · #1 ·
So I've got everything for my rebuild: Crower rods, forged pistons, Jim Wolf cams..ect.

PROBLEM: I ordered new crank and bearings. The crank shaft journal bearings are too thick. Upon asking the parts department where ordered, I was told Nissan has over 20 'grades' of bearings and they have no way to discern the thickness of them from the parts list. Its been sitting for about two months trying to address this issue. Yes, I did order them according to my VIN number but still have had no luck. Anyone with any inside information about which grade of crank journal bearings to order. BTW.. the piston rod bearings are correct but the main crank bearings are not.
 

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OK, so you need to get or get access to the Service Manual... it's all in there.

The block and crank will have markings on them that list the grades for the main bearing housing and main journal diameters, respectively. Manual shows location and how to decode the markings. Bearing grade selection is also explained in the Manual. The attached table shows the dimensions, and there are two additional, large tables regarding bearing selection based on the crank and block markings (different tables for journals 1&5 and journals 2,3&4).

Yes, the parts list includes about 20 options for grades 0 to 8, with some bearing sets that have two sizes, with different grades #'s, upper and lower. Your parts man should know this stuff, or you need a new parts man.

But I have to ask, why a new crank? Since you are going with new performance rods, pistons, etc, why not undersize the crank, line bore the block (that's a good idea since it assures things are square and aligned, anyway), and use Clevite bearings to match the crank grind? More machining cost, but may be a cost-effective alternative, since it doesn't require a new crank.

You can access the Service Manual for your model year by joining the NICOclub forum.

Hope this helps.
 

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So I've got everything for my rebuild: Crower rods, forged pistons, Jim Wolf cams..ect.

PROBLEM: I ordered new crank and bearings. The crank shaft journal bearings are too thick. Upon asking the parts department where ordered, I was told Nissan has over 20 'grades' of bearings and they have no way to discern the thickness of them from the parts list. Its been sitting for about two months trying to address this issue. Yes, I did order them according to my VIN number but still have had no luck. Anyone with any inside information about which grade of crank journal bearings to order. BTW.. the piston rod bearings are correct but the main crank bearings are not.
if the color codes are worn off (which I bet) you have to send the thing to a machine shop so they can turn your crank to match the bearings.
You WANT to do this so your crank is smooth. I suspect on a rebuild you had to have some lower end noise, that only makes sense for a rebuild so you must get the crank turned!
 

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if the color codes are worn off (which I bet) you have to send the thing to a machine shop so they can turn your crank to match the bearings.
You WANT to do this so your crank is smooth. I suspect on a rebuild you had to have some lower end noise, that only makes sense for a rebuild so you must get the crank turned!
Um, he said he ordered a new crank...

but I'm with you, line bore and grind the original crank, if it's still serviceable. Then you know what you have.
 

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Discussion Starter · #5 ·
Oil pump went out and toasted original block so i bought another. In tbe pricess, the besrings scarred the crank beyond repair. The block i purchased only needed a little surfacing to match the bore of the new pistons. That being said, we just ordered a new crank and bearings. We only know the block came out of a Titan.
 

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Oil pump went out and toasted original block so i bought another. In the process, the bearings scarred the crank beyond repair. The block i purchased only needed a little surfacing to match the bore of the new pistons. That being said, we just ordered a new crank and bearings. We only know the block came out of a Titan.
Ah. The block will carry the grade markings for the main bearing housings. New crank will have the grades marked for the journals.

Still, unknown block history, I would consider line boring the block, since you are adding the other performance parts, which suggests you are going to push it a bit. At least have your machine shop check it. If the block is out of square, that's no bueno, regardless new bearings and crank.

Good luck!
 

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Sit the block out in the weather for a month. then have the machine shop turn the crank , match bearings, bore the cylinders out and match bigger pistons. Sounds funny, but its a old hot rod builder trick :)
 

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^^^ Works.

(Doesn't really need to be in the weather, per say, but a bare block will "move" a bit once the tension on the head bolts, etc is released, and the trick is to get a high mileage block that is well "seasoned," and let the block rest before machining. Machine with torque plates in place, if you want to stress the engine, as in a high performance rebuild.)
 
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Aye!
The correct term is align bore. To align the center axis of the crank through the engine block from end to end.
Please don't take that the wrong way.
Everybody makes the line bore mistake and I don't want you guys to get redassed by some crusty old fvcker.
 

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Yeah, you're right of course, Walrus. TomAto, tomato... lines up the bearing journals, hence the confusion. But it also aligns the crank center axis square to the bores if done correctly.

No worries, Walrus, says one old crusty fellow (that must be what you meant in that unfortunate typo, right?) to another...
 

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It's all geometric when you're a crusty old guy.
I felt like an idiot when I learned that decades ago.
 

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Discussion Starter · #14 ·
Sorry I am slow to respond. My F250 6.0 work truck EGR system went out so I down 2 vehicles while they bullet proof it.

Yes, you are correct. There is no color codes on the replacement block but there are numbers stamped. Are they any help?

Am I to understand the new crank should have some codes to help determine the crank journal grades? Will it vary by block?

What would be the reasoning for so many different cranks and bearings from Nissan?

I really appreciate the help. The truck originally went down January 2016. I ordered parts from a scam artist in the Dallas/Fort Worth area and came just short of filing lawsuit 5 months later when I got reimbursed. It then took 2 months to reorder and receive the parts. My mechanic then took to a little sickness and took a short while to get over it and here I am trying to put the final piece together.
 

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Sorry I am slow to respond. My F250 6.0 work truck EGR system went out so I down 2 vehicles while they bullet proof it.

Yes, you are correct. There is no color codes on the replacement block but there are numbers stamped. Are they any help?
Yes, you need those numbers if you are going to fit new Nissan bearings, and you chose not to align bore the engine. Color codes are only on bearings, not the block.

Am I to understand the new crank should have some codes to help determine the crank journal grades?
Yes, there will be numbers on the crank.

Will it vary by block?
The numbers on the block are used in conjunction with the numbers on the crank to select the correct bearing sets - which may be different for every journal - and every crank/block pair will be different. Bearings are selected using the tables in the Service Manual, which translate the code numbers from the crank and block into the correct set for each journal. Different journals use different tables, as explained in the SM.

What would be the reasoning for so many different cranks and bearings from Nissan?
Because every journal of every block/crank pair may need a different thickness set to get the clearance in spec. Complicated, yes. Makes align boring more attractive, in my opinion.

I really appreciate the help. The truck originally went down January 2016. I ordered parts from a scam artist in the Dallas/Fort Worth area and came just short of filing lawsuit 5 months later when I got reimbursed. It then took 2 months to reorder and receive the parts. My mechanic then took to a little sickness and took a short while to get over it and here I am trying to put the final piece together.
No problem. You really need to take a look at the SM, since it explains in much more detail than I can type... If you don't have it, you can get access by going to the NICOclub forum, joining and accessing their Titan service manual set, year specific. Start here: How To Use NICOclub.com?s Factory Service Manual Database

Good luck!
 
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