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New crank cracked?

General engine tech -- Drag Racing to Circle Track

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miniv8
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Re: New crank cracked?

Post by miniv8 » Thu Apr 11, 2019 9:01 am

Step one: Bathe the crank in kerosene
Step two: tap it with a hammer while wet
Step three: dry it completely off
Step four: collect a handful of shop dust and cover the crank in it
Step five: tap it with the hammer again until the dust comes off your crank and look for wet spots

Source: YT-video shared on Speedtalk

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Dave Koehler
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Re: New crank cracked?

Post by Dave Koehler » Thu Apr 11, 2019 9:20 am

There ya go! How soon we forget.
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1972ho
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Re: New crank cracked?

Post by 1972ho » Thu Apr 11, 2019 10:38 am

Here is a good example of a crank someone needs advice on,351 cleveland crank.
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Re: New crank cracked?

Post by Dave Koehler » Thu Apr 11, 2019 11:01 am

welded journal. Always tough call on whether it's a real crack or a weld void / overlap.
Even a nicely welded cranks looks like doo doo under the black light.
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AC sports
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Re: New crank cracked?

Post by AC sports » Thu Apr 11, 2019 12:51 pm

Here are some closer pix. Best I can do.
May actually be forging void as suggested.
Safe to run?
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Re: New crank cracked?

Post by miniv8 » Thu Apr 11, 2019 1:15 pm

I'd run that, yeah.
Looks very much like a casting/machining overlap, and its on the backside anyways.
If the ocd kicks in hard just have it ground.

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Re: New crank cracked?

Post by GRTfast » Thu Apr 11, 2019 4:59 pm

Truckedup wrote:
Thu Apr 11, 2019 8:26 am
MotionMachine wrote:
Thu Apr 11, 2019 8:21 am
bigmike wrote:
Thu Apr 11, 2019 4:16 am
That is a forging void.
I tend to agree with this. Especially considering it's in line with the forging seam. When I've seen cracks like in the pic Scotty posted, they were caused from heat, just like cracks in the face of a flywheel. I've tried to grind them out but rarely do they go away with a minimal grind. Since the crank is new, it hasn't been subject to any trauma. I think it just didn't clean up completely from the rough forging when it was ground.
If so, is the crank usable for high performance ? Grind it undersize to try and clean it up?
I wouldn't use it without cleaning it up. Any surface discontinuity is a stress riser. It will probably be fine, but I tend to err on the side of caution if given the option.

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Re: New crank cracked?

Post by exhaustgases » Thu Apr 11, 2019 6:29 pm

1972ho wrote:
Thu Apr 11, 2019 10:38 am
Here is a good example of a crank someone needs advice on,351 cleveland crank.
Looks like some welding porosity and could be hydrogen cracking of the weld. If its cracked its just going to grow, and the porosity is not a good thing either especially in the radius. And like the last post from GRT as well.

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Re: New crank cracked?

Post by MadBill » Fri Apr 12, 2019 11:10 pm

Cracks don't stop and re-start as in the first of the close up pix. I bet the crank rings vs. thuds if it's hung on a wire and tapped with a hammer.
Also, it's in a low stress region. I run it with no worries.
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Re: New crank cracked?

Post by Dan Timberlake » Sun Apr 14, 2019 9:16 am

For OP, not RE: that nasty-*ss welded crank.

I agree the "seam" is not in the worst orientation, and assume it does truly not extend into the fillet/radius, although visual is not the best way to ascertain that.

Is this build it and forget it?

Or, is the pan going to come off several times a year for inspection, so the crack/seam could dye penetrant tested to monitor "progess?"

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Re: New crank cracked?

Post by AC sports » Mon Apr 15, 2019 7:33 am

Ideally I don't want to touch it after building but I won't sleep easy. It does continue into the radius which is why I'm concerned. Even if it's a welding void, surely it can't be good in the radius. Barely visible there...but nonetheless.

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Re: New crank cracked?

Post by Dave Koehler » Mon Apr 15, 2019 10:00 am

AC sports wrote:
Mon Apr 15, 2019 7:33 am
Ideally I don't want to touch it after building but I won't sleep easy. It does continue into the radius which is why I'm concerned. Even if it's a welding void, surely it can't be good in the radius. Barely visible there...but nonetheless.
uhhh, wait a minute. After all this you still haven't had it tested? That's on you.
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Re: New crank cracked?

Post by AC sports » Mon Apr 15, 2019 12:16 pm

Nowhere local to test it unfortunately , hence my post asking for opinions.

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Re: New crank cracked?

Post by Dave Koehler » Mon Apr 15, 2019 10:28 pm

OK, but you have been shown how to check it yourself via 2 or 3 methods, ranging from free to not real expensive. Become that guy.
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