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The block had the center three caps were splayed and I had replaced the outer allen head holts with grade 8 bolts because I couldn't torque the allen heads.

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My engine is apart getting a new block and pistons. Took everything in yesterday and they told me that my K1 crank that had 5 passes on it is cracked in 20 places with the biggest being over a inch long and the crank is bent.

My question is what could have caused this? I had Reher-Morrison perform the balance on it when it was new so they should have known if it was bent, right? I pulled the motor out because the oil pressure was getting low and it kept lugging down and stalling to find the center three main bearings with what looked to be overheated. The block had the center three caps were splayed and I had replaced the outer allen head holts with grade 8 bolts because I couldn't torque the allen heads.

So what came first? Was the line hone distorted from the now fully torqued main caps, or was the crank bent to begin with? The crank is junk and will need to be replaced but I am curious as to why this happened. It's my first bent crank and it's almost brand new. Here is a pic of the main bearings.

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Worst set of bearings I have ever seen from a 5 pass motor. Looks like insufficient bearing clearance likely caused by a bent crank or improper torque either at assembly or when machining was done.

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What is really wild is that the two main bearings on the ends looked fine. Had .0024 main bearing clearance.

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First off, you are making good power to run that fast at 3300 lbs. That said, I hope you either have an aftermarket block, or are working with a low deck B motor based around the 400 block. To me, it is all about keeping the rotating weight down to the minimum, and keep a good eye on clearances during assembly. I started off just like you did, not much mentorship. But guys on the board here helped tremendously.
If you don't have mikes and gauges to measure every last part you are going to put together, get them. They are a lot cheaper in the long run than situations like this.
I have a full set of outside mikes, a GOOD dial bore gauge, dial indicators, etc and use them all. Even the best shops can have something slip by.
That said, Reher Morrison is someone I do business with when ever I can. They are great to deal with, and I trust their work and reputation. So that leads me to believe the cause of all this is not with their work. Also, I own their engine assembly books. I suggest you read all their tech articles on line as well.
You have suffered the pain and expense of a motor gone sour, now it is time to reap the rewards of a very well done build! A new plan for a shortblock is in order, so ask what the guys are running.
My personal favorite is like 440jims 512 lowdeck combo, a 512 cube 4.25 stroke 4.375 bore lowdeck motor with a very light bobweight. An aluminum rod motor set up this way with aluminum caps, and a girdle will handle about anything you can throw at it and live due to a bobweight of about 2000 grams. A RB motor like mine comes in at 2432 and is steel rod, and flexes the megablock I have bad enough to cause me grief. It lives, makes great power, but I would be better off with a lowdeck 4.5 bore deal!
Last, but not least, is oil control and flow. Did you ever have even a small dip in oil pressure during braking? all oil passages the proper size, at least 10 psi per 1,000 rpm? minimum 15w40 or preffered 20w50 race oil? A good pan with a side bucket? All this is important, and I paid money in the form of hurt parts to learn it.

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The rod bearings looked good as well. They were a little messed up from the junk from the main bearings. I suspected that the three center main caps were the culprit once I pulled it down. I assume the outer bolts never were torqued to begin with on the original build. This block is not being reused. I have a tall deck R3 at the machine shop right now. It was a 4.00 crank and it saw 7000rpm two times.

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gregsdart this is not my big block I'm having problems with. The 499 in my Challenger that I built 2 years ago is still running great. I did use a Mega block and a good assembly in it. This motor I'm building now is for the Dart Sport I purchased a year and a half ago that came with a stroker small block that I wanted more e.t. out of to go race Super Street and some Quick Door races. I started with all new stuff except the block. Now it will be all new. It did manage to run a [Email]6.42@106[/Email] before the problems occured. Next build will be a tall deck R3 and custom dome Diamond pistons.

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"My own opinion is its better to use a good ProGram 2 bolt cap and studs than a 4 bolt conversion on the stock block stuff."

This is also my opinion and exactly what I did with my 416.

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I have read this same thing many times, Im using good caps, and a hughes main girdle on my stroker build...

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The block had the center three caps were splayed and I had replaced the outer allen head holts with grade 8 bolts because I couldn't torque the allen heads.

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This is a red flag for me, don't really know what it means.The main cap bolts or studs should be torqued the same while being line bored as they are while being run. Other than that it looks like assembly error to go that bad that fast. Insufficient bearing clearance?

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"My own opinion is its better to use a good ProGram 2 bolt cap and studs than a 4 bolt conversion on the stock block stuff."

This is also my opinion and exactly what I did with my 416.

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I have read this same thing many times, Im using good caps, and a hughes main girdle on my stroker build...

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, third season on pro gram 2 bolt caps w/studs turning in the 7ks stock 59* block stroker, its the major thrust thickness that spooks me