Would you trust this piston? (broken valve spring)
07-06-2010, 12:13 AM
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Would you trust this piston? (broken valve spring) 
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?
07-06-2010, 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.
burring from the valve contact.
You will want to brush that down to prevent hot spots and detonation.
07-06-2010, 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
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
07-06-2010, 03:13 PM
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"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)
07-06-2010, 03:53 PM
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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)
"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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07-06-2010, 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.
07-06-2010, 04:31 PM
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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!
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!
