Ls7 heads dropping valves
04-30-2013, 11:09 AM
#81
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I am interesting in buying a Z06 for trackdays. Do you see this issue on the 2011 or later Z06s? Are there any other issues with C6 Z06?
Thank you.
CYe
04-30-2013, 11:57 AM
#82
Have you seen my Z06 for sale? Very track capable.
https://ls1tech.com/forums/vehicle-c...p-2850lbs.html
what about all those 06's that are dropping like flies. they all have the same problem
05-23-2013, 09:40 AM
#88
Its been a while since I've trolled through this section but i'll spiff ball a theory out there.
Too much rocker arm leverage perhaps? Unstable rocker movement creating excessive side loads on the valves jamming them in the guide and wearing the tips off and the guides out? LS3 heads are very similar in design and the arm ratio is less so maybe thats the straw for the LS7 heads?
Just plain too much for bread for buckskin
Too much rocker arm leverage perhaps? Unstable rocker movement creating excessive side loads on the valves jamming them in the guide and wearing the tips off and the guides out? LS3 heads are very similar in design and the arm ratio is less so maybe thats the straw for the LS7 heads?
Just plain too much for bread for buckskin
08-28-2013, 09:04 PM
#89
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08-29-2013, 12:49 PM
#91
Yeah I can't believe it's purely because of the hollow intake and sodium filled exhaust stems. The LS6 heads were designed that way and I haven't ever heard of them having valve failure issues after all these years. Would think it must be related to the seat material or geometry.
08-30-2013, 03:14 PM
#92
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08-30-2013, 10:02 PM
#94
Is this guide wear solely due to cooking the oil as stated above? Is there any chance this is somewhat caused by the rockers not being roller tipped? You know, like why TFS typically require RRs?
08-31-2013, 05:31 PM
#95
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It is a mystery. There are lots of theories, some based on skewed data, and no true smoking gun. I think the main problem is that no one is really investigating it in a scientific/engineering manner, but to do so properly would cost a fair sum of money (five figures at least) so we're left with mostly anecdotal reports, some of then 2nd hand.
08-31-2013, 05:37 PM
#96
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09-10-2013, 07:33 AM
#97
sorry it took so long to get back with you. Well the guy with 30k had something come up an it will be about 3 weeks before i can get his car to check. with that said I have some bad news. just checked an 06z 2nd engine, build was 10-11 on the gm crate. guy had a well known cylinder head shop do his heads, bronze valve guides ss valves, at my advise I told him a few years ago to run the YT rockers, full ported heads cam fast intake 550rwhp car with now 10k miles 34 1/4 mile passes, street pulls, an a weekend driver on the street. pulled the back 4 rockers and springs on pass side of car. I didn't even bother to ckeck the clearnce guides are shot all 4 are bad that I checked. heads have to come off.this is a friend of mine so I know he don't beat the car to death this should not be in any car with this little miles. I will post the wiggle test tomorrow if I get time. if not I'll post it up soon. I will be pulling the heads on this car this week to see how bad they really are. but from seeing the wiggle an 3 out of 4 valve seals cracked from heat it's not good. guides have No wear from side to side, all up an down just like all the other shot heads I've checked. I will be updating vids very soon after they are off the car. also the car AF was set at 12.2 I'm starting to think mybe after market heads are the best bet at this point. who knows. I ran the same set up but I used all pro heads and my guides are good
09-10-2013, 06:04 PM
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09-10-2013, 08:04 PM
#99
Seems to me any Hollow stem Valve is just asking for trouble....My C5 Zo6 now has a Ls2 Long Block sitting in it because the Ls6 Exhaust Valve failed because of heat (NOT a valve spring issue) and blew the motor. Thankfully it was the guy before me that this happened to and he was nice enought to put a Ls2 out of a GTO in the car w a Cam and other goddies before I bought it.
BUT this happened alot in the C5 Zo6 cars also because of this reason AND YES because of faulty valve springs.
NOW my Lsx 427Ci Ls7 (<GM Factory Heads) top end Firehawk I owned 252/255 .670 .670 etc etc Cam didnt have an issue, the Valve train was by far the quitest I've ever herd out of an Ls Cammed Motor still to this day
Factory Rockers w Comp Trunion upgrade, Lunati Link Bar Lifters
Cars been running strong for going on 3 seasons now and never been apart......
Also why would Bronze Valve guides fix the issue?! Slap me if im wrong but unless your relocating the guide to correct whats off location.......The Bronze Guides are softer than the Factory Powdered Metal and arn't the Factory Guides lubricant impregnated also?!
BUT this happened alot in the C5 Zo6 cars also because of this reason AND YES because of faulty valve springs.
NOW my Lsx 427Ci Ls7 (<GM Factory Heads) top end Firehawk I owned 252/255 .670 .670 etc etc Cam didnt have an issue, the Valve train was by far the quitest I've ever herd out of an Ls Cammed Motor still to this day
Factory Rockers w Comp Trunion upgrade, Lunati Link Bar Lifters
Cars been running strong for going on 3 seasons now and never been apart......
Also why would Bronze Valve guides fix the issue?! Slap me if im wrong but unless your relocating the guide to correct whats off location.......The Bronze Guides are softer than the Factory Powdered Metal and arn't the Factory Guides lubricant impregnated also?!
Last edited by 1999Firehawkls7; 09-10-2013 at 08:26 PM.
09-14-2013, 03:25 PM
#100
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sorry it took so long to get back with you. Well the guy with 30k had something come up an it will be about 3 weeks before i can get his car to check. with that said I have some bad news. just checked an 06z 2nd engine, build was 10-11 on the gm crate. guy had a well known cylinder head shop do his heads, bronze valve guides ss valves, at my advise I told him a few years ago to run the YT rockers, full ported heads cam fast intake 550rwhp car with now 10k miles 34 1/4 mile passes, street pulls, an a weekend driver on the street. pulled the back 4 rockers and springs on pass side of car. I didn't even bother to ckeck the clearnce guides are shot all 4 are bad that I checked. heads have to come off.this is a friend of mine so I know he don't beat the car to death this should not be in any car with this little miles. I will post the wiggle test tomorrow if I get time. if not I'll post it up soon. I will be pulling the heads on this car this week to see how bad they really are. but from seeing the wiggle an 3 out of 4 valve seals cracked from heat it's not good. guides have No wear from side to side, all up an down just like all the other shot heads I've checked. I will be updating vids very soon after they are off the car. also the car AF was set at 12.2 I'm starting to think mybe after market heads are the best bet at this point. who knows. I ran the same set up but I used all pro heads and my guides are good