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Molnar Rod bearing clearance

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Old May 27, 2025 | 06:10 PM
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Default Molnar Rod bearing clearance
I am checking my rod bearing clearance - Molnar Power Adder rods and King coated CR807XPNC. They are TIGHT. I'm zeroing my Mitutoyo dial bore gauge to the mic off the crank journals (brand new Molnar crank) and getting about .0017.

If I order STDX, I should be able to get to .0027. That's not too loose for a DD with a small cam and about 14psi from a D1SC?

Mains came in at .0022 across the board. Aluminum 6.2L.
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Old May 27, 2025 | 06:16 PM
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Order the X bearings and half shell them…std on beam and X in the cap. Should give you .0023ish. Do not run .0017 with a power adder.
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Old May 27, 2025 | 07:42 PM
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Originally Posted by Che70velle
Order the X bearings and half shell them…std on beam and X in the cap. Should give you .0023ish. Do not run .0017 with a power adder.
Appreciate it! Does the x shell go in the rod end or cap end?
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Old May 27, 2025 | 07:50 PM
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I put X’s in the caps. Measure to make sure you are where you need to be…mock it up. You gotta build the engine before you build the engine. Mock up everything.
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Old May 28, 2025 | 09:04 AM
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Originally Posted by Che70velle
I put X’s in the caps. Measure to make sure you are where you need to be…mock it up. You gotta build the engine before you build the engine. Mock up everything.
Again, I appreciate it!

Exactly what I am doing. Bought a rod vise, dial bore gauge and micrometer to hopefully ensure this is the last time this particular motor comes out of the truck. Measuring every journal and bearing diameter to ensure proper clearance across board.
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Old May 30, 2025 | 11:12 PM
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The STDX bearings came in tonight so I installed 1 in the cap of my test rod and retorqued to 30lbs + 60*. I ended up right around .0024-.0025. Might be overkill but I'm going to install a std and X and measure every rod to be safe.

Thank you again!
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Old May 31, 2025 | 10:07 AM
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.0024-.0025 is what I’d shoot for here. What oil pump are you running? Your gonna need some volume to make this live.
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Old May 31, 2025 | 10:28 AM
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0.0022 main clearance on an AL block is on the loose side. The AL block grows more with heat that an iron block, probably about 0.0005 on the mains. You'll want to run at least a 10w40 oil.
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Old May 31, 2025 | 11:16 AM
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Originally Posted by pannetron
0.0022 main clearance on an AL block is on the loose side. The AL block grows more with heat that an iron block, probably about 0.0005 on the mains. You'll want to run at least a 10w40 oil.
You have to set bearing clearances up according to power level. It’s loose, yes. He is going to need a 10296 pump here. I’ve built many aluminum LS engines at .0025 that make big power and run 30w oil with the correct pump.
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Old Jun 2, 2025 | 07:58 PM
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My main bearings range from 0.0024-0.0027 on my LS7, I run Redline 20w50 with a Katech LS9 (red) oil pump and it seems to be good so far. About 1600 miles and I'm pretty hard on it.
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