I agree with Checkmate, the crank must have had a crack. Also agree that if it did have a crack, sudden reverse shock could have made the crack propagate. As for the magnaflux job, I do that kind of non-destructive examination at my job. It is not all that complicated of a process but the part that takes extra care and attention is interpretation of indications (possible cracks). There are a ton of boneheads out there that wouldn't know what a mag partical (magnaflux) indication or actual crack looks like even if they fell in it. Plus, these guys can tell you they magnafluxed it but who really knows? Sleezy *$!@@!*$ all over the place out there! You have to get that kind of work done at a truely reputable shop (or bring it to me and I'll do it right). I feel bad for your buddy about the crank - about the wall though, did he have "beer-vision" that night????

Quote:

Originally posted by Cord
The crank was used. It was second hand from a third party. And you want the builder to cover it? If you want the part to be covered, then it should have come from the builder. When he supplied the part, he assumed the liability.

That said, a buddy built a engine back in high school. He got about 45 miles on it when the crank broke. Turned out he forgot to torque one of the caps. Must of tried hitting the final torque value in one step.

do anything for him. Not the engine builder who built the motor for him. DID THAT MAKE SENSE

when you tear the engine down it shouldn't be too hard to figure out what happened. cut the oil filter open and look for metal, metal chips, or shavings in the oil pan, lay the main bearings out in order and look for signs of scoring from loss of oil and compare them to the journal that broke. a cracked piston ring or broken valve, gouges in the cylinder wall could indicate seizing of a piston. if there are no cylinder gouges, melted bearings, blue pistons, chips or shavings, and the caps were tight, i would guess you had a defective crank.
going from forward to full reverse is not a good thing but worse for the drive than the engine. the engine still spins the same direction just under more load. i'm surprised the drive survived.
sorry to hear of the damage, lunati has a pretty good reputation. they aren't cheap cranks.

Either way Mike, it doesn't change the response. If somebody bought a crank from you and broke it, would you cover it? No. You don't know anything about how the engine was built. If the builder used the wrong clearances, why should the crank seller cover the crank? If the crank was defective, why should the builder cover it? The buyer took that responsibility when he bought the part.

I bought a used 427 crank for my hot rod one time from a guy who was a reputable source for hi perf used chevy engine parts. He said, "It was just magnafluxed and turned .030 on the rods and .020 on the mains". It had a tag with the sizes on it and it was in a bag from a machine shop. I should have known from the journal sizes it had been around the block a few times, but I bought anyway and took it to my crank grinder to have him check it out........ 3 cracks. When I called the guy back, he got mad at me for having it checked before installing it in my motor. WTF... I asked for my money back ($350) and he said no way. I ended up giving it back and getting "store credit". I got a $200 dominator intake and a $50 set of valve covers. Now I only feel half screwed...... I feel bad knowing that somebody probably bought and used it.

Where exactly did it break?

Will find out this weekend

Lunati does make good cranks.
I think a lot of it depends upon the stresses placed upon the crank. For example, we used to run 304 inch small blocks in NHRA comp eliminator to 10000 rpm.
We found cranked cranks all the time and ran them another 40 runs before trashing them. Why? In that setup, clearances are loose, very short stroke, and very light load. Cranks will last forever in that application. Valve trains are a different story
I guess what I am saying is that with the load and stress put on a high torque big block, any small crack in the crank can become problem real quick.
Used is used, your buddy is out of luck.

I broke one in two after only 10 hours, forged GM crank, never over 5000 RPM. It had been mag'd just before installation. Journals were cut undesize .010 from a prior spun bearing, but it didn't break near the journals with the bearing damage. I'll dig up a picture from my system at work on Monday if you want.
Broke right behind first throw, actually still ran that way but made some noise and oil pressure was way low .
-Greg

Engine builders have the upper hand in that there are so many other variables that must be considered before a warranty will be covered. Add in used parts and it may be impossible to really prove the engine builder is at fault. If it failed on the dyno or on initial fire up then there is a stronger arguement against the builder. If it lived 45 HRS, forget it. All a good engine builder can do is be sympathetic. My builder gets dirt cheap on his labor in the winter so if guys need some help he is glad to do it then for real good prices. The only other thing is to try getting the crank manufacturer involved, but I doubt they will do anything on a part with unknown previous useage and time. I learned a long time ago that used parts can be cheaper and more expensive than new ones.