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LS7 Valve Train and Engine Failures

Quote:

Originally Posted by Vettezuki (Post 121996)

Yeah, I was going pot post about what looks like a smaller displacement TT for the new ZO7. Interesting . . . if it's forged everything from the factor, could be a ridiculous tuners platform out of the box. . . for those who want more than 600bhp.:smack:

Lets hope they don't skimp on the valve train like they did with the LS7.

Quote:

Originally Posted by Shaolin Crane (Post 121997)

Lets hope they don't skimp on the valve train like they did with the LS7.

Que?

Quote:

Originally Posted by Vettezuki (Post 121998)

Que?

Tons of LS7 headed/engines have serious valve train issues. GM only used something like 120lb springs with a 2 Piece, hollow sodium filled exhaust valve, yet used a Ti Intake valve. Stock untouched engines were dropping valves pretty commonly and any cammed car would snap the valve. Since the spring rates were so low it would cause oiling issues, then the guides wear faster than normal and bam, dun gon fucked up ya motor. Made it pretty mandatory to change out at least the exhaust valves.

Sound like bullshit.

Well there about as much fact and sense in both post. Kind of the standard. I guess I did hear about some motors having the valve seats walk before they had any significant miles on them,
:worf:
however that wasn't an LS7.

I remember some people complaining, and definitely some catastrophic engine failures. But noone ever conclusively pinned it any of the above.

GM DID specifically identify a problem some subset of heads and the valve guide.

Quote:

Hello all,

LS7 Valve guide issue summary:
• Affects a small, number of '08, 09 ’10 and ’11 Z06’s
• GM discovered the condition through our cylinder head warranty data involving a very small percentage of our vehicles.
• Through inspection of returned heads, it was determined that a machining error in the valve guide had occurred at our head supplier.
• The quality issue has been contained as of Feb 2011 with 100% inspection of all heads.
• The most common customer complaint has been excessive valve train noise.
However if the condition is not addressed, it could result in engine failure. To date, where this condition has been observed, it has occurred early in the vehicle life.
What customers need to know: They should drive and enjoy their vehicles without fear. If their car demonstrates this condition, they are likely to hear unusual valvetrain noise first. If you have a concern regarding this issue on your personal vehicle feel free to contact me through private message on this forum and we will work to assist in resolving your concern. Feel free to contact me through Socialmedia@gm.com please put attention Evan in the subject. As always, vehicles that have modifications to the powertrain or the calibrations, are no longer covered by GM's warranty.

Sincerely,
Evan, Chevrolet Customer Service

http://forums.corvetteforum.com/c6-z...-e-phenom.html
http://ls1tech.com/articles/gm-issue...e-wear-on-ls7/
http://ls1tech.com/forums/generation...-problems.html
http://ls1tech.com/forums/generation...ng-valves.html
http://ls1tech.com/forums/texas-memb...lve-issue.html
http://forums.corvetteforum.com/c6-z...ust-valve.html
http://forums.corvetteforum.com/c6-z...-pictures.html
http://forums.corvetteforum.com/c6-z...e-failure.html

Rock solid valetrain, by all means, stuff a cam in that and leave it alone, run it hard, I don't give a shit. I've had my hands on my LS7 heads than i'm sure anyone here, seen the failures personally, run a 2 piece valve, all the hard core guys do, run some low pressure springs too, that's what up. :rolleyes:

http://lmgtfy.com/?q=ls7+exhaust+valve+failure

Ben I was already aware of the valve guide issue. It is "contained" as of 2011.

I seriously think some people either can't don't read the articles they post or are not capable of reading for comprehension. So you post multiple threads about a valve train issue. Every thread debates on whether there is an issue or not. You cla that the factory went cheap on valves and springs, but the threads reference a rocker arm fix. You claim the issues is with canned cars but the last thread had a pretty telling poll: 10 dropped valves on stock motor and tune, 5 on stock motor with tune, and 5 on crammed motors. Looks like we are less likely to see failure on crammed motors.
The reality is that any give my track day there is always a Z06. There will be failures. I felt fortunate to have my first motor last three years with the amount of abuse it takes.
Up had your hands on a bunch of Z06 heads right. Kinda like all that road experience you said you had.