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Discussion Starter #1
Going to start a new build. Wondering what guys run for main clearances in aluminum blocks. 4" stroke spinning 8000 rpms. For that rpm I was thinking staying on the loose side for room for crank flex. Im most likely going to add the DM girdle to the mains to help stiffen it up. Would like to hear some opinions on clearances.
 

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Contact ER racing thru PM or he may post with help.
 

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I run my LS2 at .022-.0025 on the mains/rods. That is stock stroke, under 7500rpm, had planned for boost. What block are you running that crank in? Some will say I'm totally wrong, but I would never run that much rpm w/ 4in crank in a stock sleeve LS2/LS3 block. The mains will flex all over the place(I think the girdles are a waste), the piston is getting pulled out of the sleeve and adding that much piston speed/leverage to the equation makes for a bad idea. I did have the idea to make a 3.825 or 3.900 mini stroke and turn it up, but decided the better $$$ spent is a big bore block and get some amazing cylinder heads. I have melted my brain w/ combos and it all comes back to bore size. If you are using a LS2/LS3 block, just stay std stroke and put the $$$ in the valvetrain/heads. Launch is doing a similar build right now(LS2), check out his posts on the forum.
 

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Discussion Starter #4
Its going to be in a re sleeved block with longer sleeves.



I had a 418 stock LS3 block 4inch stroke spinning it over 8000. Finally spun a bearing, snapped a rod and broke the block. Ran it for 2 years like that.
 

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Ok, w/ sleeve block you are good to go. I would upgrade the main caps, maybe some LS9 or ProGram Engineering ones and let it rip. Light rods/pistons are recommended. Clearance wise, I would still be around .0022-.0025. Alum block supposedly expands and the main clearance will increase a touch w/ it at operating temp. I don't think running it super loose will help. What crank are you running?
 

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i shoot for .002.figure the expansions prob good for .0005 growth but im no pro..hows it going to be ran? hot lapped an street drove or tune it for like 100 degree temp an us a chiller between hits all out deal
 

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Discussion Starter #10
i shoot for .002.figure the expansions prob good for .0005 growth but im no pro..hows it going to be ran? hot lapped an street drove or tune it for like 100 degree temp an us a chiller between hits all out deal

Short drive on friday night to local hang out but, mostly track. 418 I ran it loose. .0026 to .0029
 

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You should check out the blog on the CCW cranks, that sound like it's right up your alley. I would also have a solid look at your oil pan/pump and make sure it's up to snuff. What pan/pump are you running?
 

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Discussion Starter #14
You should check out the blog on the CCW cranks, that sound like it's right up your alley. I would also have a solid look at your oil pan/pump and make sure it's up to snuff. What pan/pump are you running?

I run the CTS-V pan and the improved racing baffle with a modified pump. I looked into the ccw cranks. I seen they fit ls next block and or need machine work to fit in a gm block.
 

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Hmmm, I will do some research on the pan, but have not heard any bad on it, specifically. No, check out the CCW Compstar/Callies cranks. I had the same questions, but supposedly a drop in w/ no clearance issues.
 

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The Dart CCW cranks don't have the counter weights clearances like the Callies but it's not very much work to clearance the block for them. I did my 6.0L iron block on the mill in less than 30min to a very professional quality level. You could do it with an angle grinder in a pinch. Just my $0.02
 
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