Used 406 small block

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Ok. If you have the damper, run the part number or have the balance checked. The dirty oil could be blowby or exhaust valve seals. Without the flexplate, you don't have much choice but to pull it apart.
 
Yeah that's what I thought... I tend to overthink things. I need to confirm 100% it's internally balanced, it should be and I'm like 98% sure it is though.

As you probably know 400's are externally balanced. I would get the number off the crank and see how it's balanced. While you are at it step up to an SFI approved flywheel & balancer.
 
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As you probably know 400's are externally balanced. I would get the number off the crank and see how it's balanced. While you are at it step up to an SFI approved flywheel & balancer.
Sure.... until someone internally balances it. It depends on how many slugs are in the crank.
 
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As you probably know 400's are externally balanced. I would get the number off the crank and see how it's balanced. While you are at it step up to an SFI approved flywheel & balancer.

I will definitely check it out better when I get it on a proper stand (it's in a cradle) although I know for a fact the bottom end is not at all stock with billet four bolt caps with ARP studs, H beams, and a forged crank. Doesn't mean someone didn't make a bonehead decision, but all that seems like a ton of cash to spend on a bottom end to not go internally balanced.
 
Oh boy... Well that doesn't sound good. 😕
This motor sounds almost Identical to my current ,I have a 260@ 050 crane cam solid ,I drive it everywhere ,runs extremely well mine is internally balanced ,I usually spin this motor to 7000-7200 ,200hp shot of spray ,can't wait to have my 496 done tho
 
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As you probably know 400's are externally balanced. I would get the number off the crank and see how it's balanced. While you are at it step up to an SFI approved flywheel & balancer.
Sure.... until someone internally balances it. It depends on how many slugs are in the crank.


I would say yes to both of ^^^ these.

You have two options as I see it - tear it down and check everything. Will be about $500 of you have a reasonable machine shop near you. Maybe $650 if you get it balanced (would then know exactly how it is set up.) No need to change the cam, but sure would be nice to know what it is. A hydro roller does have alot for longevity than a solid FT, but figure $1k in parts alone.

Option two - slap an SFI flexplate on for an internally balanced SBC and see if it vibrates like heck. If it doesn't then run it like you stole it for 2-300 miles.

Either way - your choice. The IK200's will easily support 500HP in'out of the box' form. If they've been worked over somewhat and have the rest of the assembly to go with them, then it could be closer to 600HP. There isn't any real way to tell/estimate HP potential without knowing the cam and compression.
 
Ik200s are really nice for the price ,I checked mine as they said we're good to 575 lift, spring pressures were with in 5lbs , bowls were cut nicely, check the balancer for part number,or on the crank, it's more then likely internally balanced
 
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