CR Rebuild Tolerances/specs

QIKDSL

QIKDSL

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Jan 2, 2008
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Ive got a 2004 CR that is at the machine shop right now getting built. Truck made upper 800s on stock internals before I pulled it out. New motor will be doing the same power if not a little more. It will be .020 over with Swain Coated QSB 480 pistons. I have done some reading and searching and seen a wide gap of opinions on specs Was hoping to narrow it down and get a for sure idea of what I need to tell my machinist. The truck is a daily driver but also weekend drag strip play toy. Looking for ring gap specs, piston to wall specs and any other bottom end specs. Thanks!
 
If it's more performance than daily driving I'm pretty sure I've heard to tell your engine builder to build it like a high performance blown motor as far as ring specs go.

Someone can correct me if wrong here
 
If its a DD, I would just run Cummins specs. 800hp isn't anything crazy, you aren't going to be running high rpm or lots of nitrous and/or boost.
 
SPEEDSHIFT said:
If its a DD, I would just run Cummins specs. 800hp isn't anything crazy, you aren't going to be running high rpm or lots of nitrous and/or boost.
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What is considered alot of boost? Last setup before the motor came out was making 72-75psi and I did use Nitrous a few times with it. More then likely be back on it again or a water/meth setup.. Just tryin to get my ducks in a row here and make sure I am on the right page with this rebuild. Searching Ive see alot of different opinions so want to make sure Im going the right direction with it.
 
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dmaxn said:
What is considered alot of boost? Last setup before the motor came out was making 72-75psi and I did use Nitrous a few times with it. More then likely be back on it again or a water/meth setup..
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SPEEDSHIFT said:
If its a DD, I would just run Cummins specs. 800hp isn't anything crazy, you aren't going to be running high rpm or lots of nitrous and/or boost.
Click to expand...

This
 
I would offer some help Jeff but I'm sure I'd get laughed out of the thread!! LOL


So I'll sit back and watch... You don't need my luck.. lol
 
Big Swole said:
I would offer some help Jeff but I'm sure I'd get laughed out of the thread!! LOL


So I'll sit back and watch... You don't need my luck.. lol
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It was defective parts man.. All 2-3-4 times!! :lolly:
 
dmaxn said:
It was defective parts man.. All 2-3-4 times!! :lolly:
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Freeze plug
mp8 harness
dual fueler box
mis cut / marked rings
crack in crank / bad rod bolt


That's my stories and I'm stickin to'em!! lol
 
I ended up at .007ptw and don't have any extra blow by. .005-.006 is what I was hoping for but to clean up the walls it took a little more. I'm running stock pistons with no coating.

I set ring gap to the loose side of factory specs.
 
I am running .005 on my PTW clearance (2006). I set my top ring gap at .019. DO NOT set your top ring at minimum clearance .011. I had a set of federalmogul top rings set at .012 and they touched! I had to pull the engine (again) and re-bore to fix. Make sure you also check your piston protrusion to ensure you get the correct head gasket. <.012 one hole, >.012 but less than .019 two hole, >.019 three hole. Hope this helps.
 
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