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Would you trust this piston? (broken valve spring)

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Old Jul 6, 2010 | 12:13 AM
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Default Would you trust this piston? (broken valve spring)

Would you trust this piston? (broken valve spring)-getattachment.aspx.jpg

Would you trust this piston? (broken valve spring)-0705002327b.jpg

This was the result of breaking a valve spring and dropping a valve at about 2000 rpm

Would you trust that piston? The gouges aren't incredibly deep, but is still a concern with a motor turning 6700 rpm and putting down 400+ at the wheels


For reference this is from my roommate's 2000 Z28, he was running a texas speed 233/239 grind with .595/.605 with comp 918's

luckily the ported Ls6 head looks to be ok, what do you guys think?
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Old Jul 6, 2010 | 12:15 AM
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I'd at least flux the piston for hair-line cracks. It seems as there is some
burring from the valve contact.

You will want to brush that down to prevent hot spots and detonation.
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Old Jul 6, 2010 | 11:48 AM
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does anyone else have any insight?

if it were me i would pull the motor, throw a new slug in it, and while it was out i would throw in a set of ARP rod bolts. But this isn't my car lol
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Old Jul 6, 2010 | 12:58 PM
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Originally Posted by Adrenaline_Z
I'd at least flux the piston for hair-line cracks. It seems as there is some
burring from the valve contact.

You will want to brush that down to prevent hot spots and detonation.
this. exactly.
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Old Jul 6, 2010 | 02:58 PM
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Originally Posted by Adrenaline_Z
I'd at least flux the piston for hair-line cracks. It seems as there is some
burring from the valve contact.

You will want to brush that down to prevent hot spots and detonation.
Are you saying to magnaflux the piston?
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Old Jul 6, 2010 | 03:13 PM
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Originally Posted by 1994Z28Lt1
does anyone else have any insight?

if it were me i would pull the motor, throw a new slug in it, and while it was out i would throw in a set of ARP rod bolts. But this isn't my car lol
I agree my next questions would be what caused the dropped valve in the first place and are the other cylinders ready to repeat this. If the heads are already off, the motor pull (at least from the top) is about 70% done anyway.

"If you don't have the time to do it right will you have the time to do it over, because "YOU WILL" be doing it over"
SSgt C.J. Brown USAF (My drill instructor)
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Old Jul 6, 2010 | 03:53 PM
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Originally Posted by Anthony Williams
I agree my next questions would be what caused the dropped valve in the first place and are the other cylinders ready to repeat this. If the heads are already off, the motor pull (at least from the top) is about 70% done anyway.

"If you don't have the time to do it right will you have the time to do it over, because "YOU WILL" be doing it over"
SSgt C.J. Brown USAF (My drill instructor)
it was caused by a broken 918 valvespring, dual valvesprings will be going back in regardless
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Old Jul 6, 2010 | 03:56 PM
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I wouldnt chance it. Looks like it took a good lick. Ls1 pistons used are cheap. I would go that route personally. yeah its alittle more work but better safe than sorry......oh and i would have that valve guide checked as well and maybe replace all the springs. could be a bad batch or something.
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Old Jul 6, 2010 | 04:31 PM
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Originally Posted by LS1MCSS
Are you saying to magnaflux the piston?
Not really appropriate with an Alum. piston huh?

Scratch that...no pun intented.

Clean the piston head and try some magnification for a closer look around
the contact area. Sometimes dirt will embed itself into the crack which
will be more apparent after cleaning.

When in doubt, throw it out. No need to chance wiping out a block and
heads for a fairly inexpensive part. Unfortunately, it's a pain to rebuild!
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Old Jul 6, 2010 | 04:36 PM
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if it was my car id run it, customers car id fix it...
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Old Jul 6, 2010 | 04:43 PM
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If $$ are an issue clean it and run it but save up for a new engine. New CTS-v LS6's long blocks are around for as little as $2600 and getting cheaper.
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