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Valves hit pistons - Questions

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Old Jan 7, 2009 | 10:39 PM
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Default Valves hit pistons - Questions

LS2 -

Timing chain broke and caused the valves to hit the pistons. A couple of the pistons are hit hard enough to feel the roughness of metal sticking up a little.

1) When the valves hit the pistons are the pistons ok to reuse? Can/should they be machined or grinded down?
2) When the valves hit the pistons does it send a shock through the crank and or bearings that would cause a concern for reusing it?

Plan is to buy a set of TFS heads and bolt it to the existing block. Just want to make sure the cam/pistons/crank, etc are ok to reuse.
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Old Jan 7, 2009 | 10:42 PM
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I would say you are okay to reuse everything. You can sand down any sharp points on the pistons to make sure you don't have hot spots.
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Old Jan 7, 2009 | 11:22 PM
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Originally Posted by 6.0monsta
LS2 -

Timing chain broke and caused the valves to hit the pistons. A couple of the pistons are hit hard enough to feel the roughness of metal sticking up a little.

1) When the valves hit the pistons are the pistons ok to reuse? Can/should they be machined or grinded down?
2) When the valves hit the pistons does it send a shock through the crank and or bearings that would cause a concern for reusing it?

Plan is to buy a set of TFS heads and bolt it to the existing block. Just want to make sure the cam/pistons/crank, etc are ok to reuse.
I'm interested in what kind of chain broke and the circumstances that caused the failure
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Old Jan 8, 2009 | 09:05 PM
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Sounds similar to this thread. You should read through it:

https://ls1tech.com/forums/generatio...n-failure.html
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Old Jan 8, 2009 | 09:18 PM
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tell us more about your engine, did you have a underdrive pulley??
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Old Jan 8, 2009 | 10:02 PM
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Ghetto flycut Now you are ready to clear that Texas Giant

Seems like several GenIV engines recently have busted TC's under suspicious circumstances running UD pulleys.

However, you should be fine if you lightly take the sharp edges off the piston eyebrows. Valves will bend before rods so I think you are ok there. So clean'em up, throw those TFS on there with a nice cam and go have some fun. Pics of the carnage would be NICE though

After reading about this I would definitely go back to a OEM balancer or better get an ATI Super Damper. They have a 10% UD and heard they just released a 25% UD not even in thir catalog yet. Those and maybe a March would be the ONLY ones I would consider. Beat on it hard and ATI is the ONLY choice I think. I guess there is a good reason so many in NASCAR run them

Sounds like you were lucky and making the best out of a tough break

GOOD LUCK

Last edited by SOMbitch; Jan 8, 2009 at 10:11 PM.
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Old Jan 9, 2009 | 05:17 PM
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looks like he may have had an aftermarket pulley

https://ls1tech.com/forums/lsx-parts...nk-pulley.html
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Old Jan 9, 2009 | 06:13 PM
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Also interested in your specific mods, possibly an ASP pulley?
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What was your VS seat pressure?
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