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sbc cracked block

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sbc cracked block

Postby Speed7 » Fri Jan 25, 2013 4:15 pm

Have a 350 four bolt main block with a hairline crack about 3 inches long down number 2 cylinder on the freeze plug side. Have any of you had luck sleeving one and it hold up in a drag racing engine? Mild build 11 to 1 compression 6800 rpm engine.
Thanks
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Re: sbc cracked block

Postby BrazilianZ28Camaro » Fri Jan 25, 2013 4:39 pm

Doing it the right way, the sleeve wouldn't be a problem.
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Re: sbc cracked block

Postby Speed7 » Fri Jan 25, 2013 5:38 pm

My concern is it is a crack, not a gouge. What would keep the crack from spreading on down the block to the oil pan rail and up to the top of the cylinder?
Thanks
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Re: sbc cracked block

Postby Speedbump » Fri Jan 25, 2013 5:42 pm

I would make sure the crack doesn't extend up into the deck and stops before it gets to the bottom of the cylinder. Then, as noted, a properly installed sleeve will work OK. A good guy might also be able to save the deck by trimming the sleeve right down to it and save the cost of decking again. Those blocks are still pretty available so be careful not to get too much money tied up in a sleeved block.
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Re: sbc cracked block

Postby BrazilianZ28Camaro » Fri Jan 25, 2013 6:03 pm

Speed7 wrote: What would keep the crack from spreading on down the block to the oil pan rail and up to the top of the cylinder?
Thanks


The best way I know to stop a crack is drill small holes on its ends.
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Re: sbc cracked block

Postby pdq67 » Fri Jan 25, 2013 6:04 pm

Might consider taking a Dremal or whatever with a short bit in it and putting an 1/8" hole at each end of the crack so that it doesn't continue to crack longer later.

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Re: sbc cracked block

Postby robert1 » Fri Jan 25, 2013 6:15 pm

It's not a problem.
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Re: sbc cracked block

Postby dontpanic » Sat Jan 26, 2013 5:18 am

I had one sleeved and with in a few races the water started showing up in the oil again, when I pulled it down the sleve cracked in the same place again. maybe bad luck?

this was a +.060 350 block 450 hp dirt track

Good Luck
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Re: sbc cracked block

Postby CNC BLOCKS » Sat Jan 26, 2013 6:44 am

dontpanic wrote:I had one sleeved and with in a few races the water started showing up in the oil again, when I pulled it down the sleve cracked in the same place again. maybe bad luck?

this was a +.060 350 block 450 hp dirt track

Good Luck


I have seen that before on performance builds.
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Re: sbc cracked block

Postby leahymtsps » Sat Jan 26, 2013 12:20 pm

this was a +.060 350 block 450 hp dirt track


How thick was the installed sleeve ? Boring some of them .060 will make them pretty thin.

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Re: sbc cracked block

Postby PackardV8 » Sat Jan 26, 2013 12:47 pm

drag racing engine? Mild build 11 to 1 compression 6800 rpm engine.
FWIW, you'll get other opinions, but the four-bolt blocks are still available for cheap. If I were building to my own preferences on most later V8s, less bore is more. The more overbore, the more problems.

Having said that, on your relatively mild build, if everything else is right, a sleeve won't be a problem. One of the better running limited budget builds out of here had three sleeves in it. I tried to talk him out of it, but somehow it ran strong and lived long.

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Re: sbc cracked block

Postby machine shop tom » Sat Jan 26, 2013 12:55 pm

A 1/8" wall sleeve properly installed with a step at the bottom will work fine. The worst thing will be that the adjacent cylinder will be pushed out-of-round and will need to be honed round again. That will open up the clearance in that cylinder.

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