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DEETOO
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Discussion Starter · #1 ·
I found this on my Mahle H series rod bearings. Some are better than others. The measured clearance is even all the way across, just the bearing halves are offset a bit they do not run into either chamfer. Anyone have seen this issue? Is it even an issue?
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If they meet concentricity, and are not defective, I would suspect they are spiral formed and axially trued. This would average a full width journal wipe area and might help to move oil across the bearing face like an auger.
 
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I have rebuilt several motors and have not seen this before.
Not sure if I agree with the help wipe oil, I've seen scratches in cam gaskets with less of a channel that practically pump oil out of the motor (not good).

To me the bearing has shifted, attached are mine from a couple years back for reference

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DEETOO
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Discussion Starter · #6 ·
The tang placement on the bearings is correct to mahle specs, however with the halves lined up the distance to the outside of the tangs is .550 the distance to the outside of the slots on the rod are .650. These are K1 rods, I don’t have any stock rods to measure. I’m going to try a set of p series as those halves are the same and should fit.
 

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Im actually more concerned that they appear twisted in the main bearing.
Offset not so much besides the potential reduced oiling and those bearing surfaces look OK (maybe)

But if you look a the edges they have been heated, you can see the blue metal. Although I have seen some bearing come like this from the factory, perhaps the heat treating step or? (didn't mention this before but your certainly make mine look new at 70K by the way.
 

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DEETOO
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Discussion Starter · #8 ·
They are new rod bearings, they may look twisted because of the angle of the pic, they are not. The color is from the plating process.
 

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DEETOO
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Discussion Starter · #9 ·
Quick update, K1 rods use the older small block style bearings CB-481 series and not the stock CB-1808 series. There are actually more bearing options in the older series (coated etc. ) I will update when the new bearings come in.
 

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DEETOO
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Discussion Starter · #10 ·
Update, confirmation on the bearing fitment for K1 rods. Finally received my CB-481HXN (X= .001 extra oil clearance, I needed it). These are the older LA engine and pre 2003 bearings. It would be nice if K1 put that info on their website to save people some headaches. I can’t wait to find out the next issue!!
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I seem to remember reading that the G1-2 engines actually used the LA "P" rod from the Direct Connection catalog.Shot peened, Magnafluxed forged quality rods. It always made me shake my head when the early tuners just threw them away when the motors were only spinning 6200.
 

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kind of a threadjack, but you guys seem to know what you're talking about. I'm trying to decide what to do with my Gen 3 2005 engine. I've got a twin turbo kit on it, making about 730whp, stock bottom end. I'd like to do a forged bottom end, and am trying to decide what route to go. I saw ROE sells a complete forged rotating assembly. Is that all I would need to be able to run a bit more boost in my engine? I was going to install larger injectors and run E-85 also. My goal is to get it to 1000whp.
So, the following questions:
  • Would I need to do anything to the crank? I see other people running custom cranks and custom cams on other turbo cars, but those cars are usually making well over 1000whp.
  • Should I be ordering oversized pistons? I did a compression test on my engine, and one cylinder was a bit lower than the rest. All of the other cylinders came back at around 180psi, one cylinder consistently showed 155psi. I know it's not a huge difference, but I scoped it and saw a couple nicks in the cylinder wall, not sure from what. I guess when the engine is rebuilt it may need to be bored to get rid of those nicks. That would probably require oversized pistons, I'm assuming. How much oversize is safe on a stock block?
  • Should I order undersize/oversize main/rod bearings?

Thanks for all your help in advance.


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Your crank is forged. You may only need to hone the cylinders for the new rings. Don't order anything over/undersized until you have disassembled and confirmed you need other than standard dimensions. That price for the package looks pretty good to me.
 

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alright thanks for your response. I'm gonna reach out to Roe to see what they have in stock. I guess I'll wait to order parts until later this year when I pull the motor and take it apart. Should I be concerned with anything else? Valvetrain, springs, push rods, lifters, etc?
 

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Update, confirmation on the bearing fitment for K1 rods. Finally received my CB-481HXN (X= .001 extra oil clearance, I needed it). These are the older LA engine and pre 2003 bearings. It would be nice if K1 put that info on their website to save people some headaches. I can’t wait to find out the next issue!!
View attachment 154014

Is this true for all K-1 rods? I have a set I was going to use on another Gen 2 build
 
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