Re: Small crack in my 426 block, Should I worry??
[Re: Dr V]
#1157781
01/16/12 05:03 PM
01/16/12 05:03 PM
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Joined: Jan 2003
Posts: 42,714 Spokane Washington
ScottSmith_Harms
Mr Wizzard
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Mr Wizzard
Joined: Jan 2003
Posts: 42,714
Spokane Washington
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Before you weld it with heat you might want to look into stitch welding that. It may be a tough area to stitch weld but anytime you can repair cast iron wiothout adding heat you will be ahead of the game. BTW, stitch welding works VERY VERY well! Stitch Welding
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Re: Small crack in my 426 block, Should I worry??
[Re: ScottSmith_Harms]
#1157782
01/16/12 05:21 PM
01/16/12 05:21 PM
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Joined: Apr 2006
Posts: 3,675 Akron, Ohio U.S.A.
roadhazard
master
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master
Joined: Apr 2006
Posts: 3,675
Akron, Ohio U.S.A.
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I agree with jcc and others about it being repaired before It looks real thin on the area where it cracked and if you have it welded I'd build up this area a little bit more so you have some wall thickness. Also I'd check into that stud being crooked. Find out why it is or what's causing it to be crooked. Could possibly be a crooked spot face where your washer sits underneath and should be remachined to it's square and pulls on the stud straight. May help eleviate some future problems with it cracking again.
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Re: Small crack in my 426 block, Should I worry??
[Re: Dr V]
#1157784
01/16/12 06:02 PM
01/16/12 06:02 PM
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Joined: Jul 2010
Posts: 2,091 Delray beach, Florida
Performance Only
top fuel
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top fuel
Joined: Jul 2010
Posts: 2,091
Delray beach, Florida
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If your planning on welding this in the car, i'm of the opinion your making a terrible mistake. welding cast iron that is under stress/ load can cause many other problems if not done properly by preheating and proper cooling techniques afterward. even then there's no guarantee the repair will last. it may appear fine after its welded, but the forming of martinsite around the weld area will weakin it.
machine shop owner and engine builder
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Re: Small crack in my 426 block, Should I worry??
[Re: ZIPPY]
#1157788
01/17/12 04:24 PM
01/17/12 04:24 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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Zippy is a factory guy, Perf Only is a pro engine builder, and I am a mechanical engineer. I agree with them. Welding cast iron is a real art and success is not guaranteed. NO WAY can it be done with the block in the car, with any reasonable expectation of success. cast iron is really special stuff and heating/cooling have to be rigorously controlled to avoid either the weld or the heat affected zone developing cracks. Plus, if the hole is drilled and tapped wrong, how is welding going to fix that? Also, welding will almost certainly tweak the block so that parts aren't square, cylindrical, etc.
How about stop-drilling the crack, drill and tap deeper for a long Helicoil, and use a longer bolt/stud? then torque to minimum.
R.
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Re: Small crack in my 426 block, Should I worry??
[Re: dogdays]
#1157789
01/17/12 04:36 PM
01/17/12 04:36 PM
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Joined: Mar 2006
Posts: 579 Wattsburg, Pa
Dr V
OP
mopar
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OP
mopar
Joined: Mar 2006
Posts: 579
Wattsburg, Pa
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Quote:
Zippy is a factory guy, Perf Only is a pro engine builder, and I am a mechanical engineer. I agree with them. Welding cast iron is a real art and success is not guaranteed. NO WAY can it be done with the block in the car, with any reasonable expectation of success. cast iron is really special stuff and heating/cooling have to be rigorously controlled to avoid either the weld or the heat affected zone developing cracks. Plus, if the hole is drilled and tapped wrong, how is welding going to fix that? Also, welding will almost certainly tweak the block so that parts aren't square, cylindrical, etc.
How about stop-drilling the crack, drill and tap deeper for a long Helicoil, and use a longer bolt/stud? then torque to minimum.
R.
Dog, we are going to look at everything tmrw. Im in no rush to fix it improperly. Im not sure how I would place a helicoil. The area that the crack is in insnt a threaded area. It is only a sleeve that the stud slides down into then a nut goes on the end. It is just a hollow cylinder that the head bolt sits into, or did I misunderstand what you meant?
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Re: Small crack in my 426 block, Should I worry??
[Re: Dr V]
#1157790
01/17/12 05:25 PM
01/17/12 05:25 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 16,376
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No, I'm embarrassed. I had pictured the hole as being threaded and if I knew everything I'd have known that it is not. Now that I've visualized it properly I don't know how I missed it before! That changes my thinking quite a bit. If it is not threaded the first thing to do is to drill a crack stopper hole at the end of the crack. Welding doesn't look like such a bad plan now. Actually the part does look like it was repaired before and too much ground off the near side. You could probably just face (cut) off the cracked part if you were sure the crack didn't extend further up under the surface, but.... Because of this I believe welding will work and the thin side could be built up, then remachined to make it really OK. R.
Last edited by dogdays; 01/17/12 05:37 PM.
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