[Z06] LS7 question
11-16-2013, 09:12 AM
#1
Drifting
Thread Starter
LS7 question
This past spring I traded in my ZO6 and got a 427 (hopefully will get a C7 ZO7 at some point). My question---in reading threads on the C6 forum I see many comments about how the LS7 engine is so bad that folks avoid buying cars with this engine. I asked on one thread if anyone had real numbers on this---specifically, did anyone know what % of the cars with issues were modified or tracked, versus those with problems that weren't modified or tracked. Someone answered and said ask on the ZO6 forum and (1) implied you folks had a ton of bad luck stories, and (2) someone had hard numbers. I never had any issues with my 2008 Z06, nor did I ever run into another Zo6 owner that did. I am concerned about my 427---is it likely to have problems? Thanks for any real insight you can offer.
11-16-2013, 09:18 AM
#2
Burning Brakes
You may want to do a search on this one as some folks here have devoted their life to this subject. There have been way too many threads on this subject and another could be painful. Just have your valves checked....wiggle test. Remove and replace if required....nuff said. 
11-16-2013, 09:52 AM
#3
I asked on one thread if anyone had real numbers on this---specifically, did anyone know what % of the cars with issues were modified or tracked, versus those with problems that weren't modified or tracked. Someone answered and said ask on the ZO6 forum and (1) implied you folks had a ton of bad luck stories, and (2) someone had hard numbers.
The root cause of the issue is debated and unknown, and accordingly no long term solution has been determined or proven.
As stated above the best advice is to try to determine if you have a (current) problem with valve guide wear by having a wiggle test done. If your guides are in spec then you likely have no problem (at this point in time). If you do have guide wear it is an indication that you could have a failure at some point and it is advised to have your heads reworked.
Some people are of the opinion that the stock exhaust valves may fail without the presence of guide wear. I am not of that belief, but I am not going to start the argument again in another thread.
11-16-2013, 10:32 AM
#4
You got a warranty so youre all good. 
There is a thread here asking if the issue was fixed in the 427, and that thread has been quite a long 1 and still going.
http://forums.corvetteforum.com/c6-z...427-verts.html
There is a thread here asking if the issue was fixed in the 427, and that thread has been quite a long 1 and still going.http://forums.corvetteforum.com/c6-z...427-verts.html
Last edited by Rupert pupkin; 11-16-2013 at 10:36 AM.
11-16-2013, 07:25 PM
#6
Team Owner
Keep it stock, and use the warranty if needed. Hopefully in 4-5 years there will be better info. If you want to mod and add power I would look at getting the heads done as part of the power adding mods.
11-16-2013, 07:32 PM
#7
This past spring I traded in my ZO6 and got a 427 (hopefully will get a C7 ZO7 at some point). My question---in reading threads on the C6 forum I see many comments about how the LS7 engine is so bad that folks avoid buying cars with this engine. I asked on one thread if anyone had real numbers on this---specifically, did anyone know what % of the cars with issues were modified or tracked, versus those with problems that weren't modified or tracked. Someone answered and said ask on the ZO6 forum and (1) implied you folks had a ton of bad luck stories, and (2) someone had hard numbers. I never had any issues with my 2008 Z06, nor did I ever run into another Zo6 owner that did. I am concerned about my 427---is it likely to have problems? Thanks for any real insight you can offer.
http://forums.corvetteforum.com/c6-z...post1585446696
11-16-2013, 07:55 PM
#8
Drifting
Thread Starter
11-16-2013, 10:21 PM
#9
Don't sweat it! If it bothers you just yank the heads and send them to reher morrison and have darin morgan take care of them. Great to deal with and my opinion is he really knows cylinder heads. Thanks Darin!
I pulled mine at 14K(07 model) cause I got a wild hair and mine had no wear at all!
Although he did take care of the exhaust valve/guides issue. I went ahead and had him CNC them and do some handporting. He also had a camshaft ground for me. I picked up well over a 100 RWHP on the same Dynojet.
If you need and of their contact info just let me know.
I pulled mine at 14K(07 model) cause I got a wild hair and mine had no wear at all!
Although he did take care of the exhaust valve/guides issue. I went ahead and had him CNC them and do some handporting. He also had a camshaft ground for me. I picked up well over a 100 RWHP on the same Dynojet.
If you need and of their contact info just let me know.
11-16-2013, 10:27 PM
#10
Don't sweat it! If it bothers you just yank the heads and send them to reher morrison and have darin morgan take care of them. Great to deal with and my opinion is he really knows cylinder heads. Thanks Darin!
I pulled mine at 14K(07 model) cause I got a wild hair and mine had no wear at all!
Although he did take care of the exhaust valve/guides issue. I went ahead and had him CNC them and do some handporting. He also had a camshaft ground for me. I picked up well over a 100 RWHP on the same Dynojet.
If you need and of their contact info just let me know.
I pulled mine at 14K(07 model) cause I got a wild hair and mine had no wear at all!
Although he did take care of the exhaust valve/guides issue. I went ahead and had him CNC them and do some handporting. He also had a camshaft ground for me. I picked up well over a 100 RWHP on the same Dynojet.
If you need and of their contact info just let me know.
11-16-2013, 10:58 PM
#11
If all that comes back good then you're golden...drive and enjoy, and avoid the gloom and doomers.
11-17-2013, 12:04 AM
#13
He CNC'd them again with one of the programs that he designed, Guides,springs, replaced exhaust valves with SS valves,seals, cleaned and valve job. They looked very nice. and seem to work very well. He flowed them but I am unsure what the numbers were off hand. Did not mill them at all.
11-17-2013, 12:08 AM
#14
He CNC'd them again with one of the programs that he designed, Guides,springs, replaced exhaust valves with SS valves,seals, cleaned and valve job. They looked very nice. and seem to work very well. He flowed them but I am unsure what the numbers were off hand. Did not mill them at all.
Don't know if you knew or not, but Darin Morgan is a member in here as well.
http://forums.corvetteforum.com/memb...in-morgan.html
11-17-2013, 12:31 AM
#15
Interesting. Thanks for the info, and congrats on the new work.
Don't know if you knew or not, but Darin Morgan is a member in here as well.
http://forums.corvetteforum.com/memb...in-morgan.html
Don't know if you knew or not, but Darin Morgan is a member in here as well.
http://forums.corvetteforum.com/memb...in-morgan.html
He has made many different combinations for LS heads...
http://rehermorrison.com/product/cnc...ylinder-heads/
11-17-2013, 08:58 AM
#16
Team Owner
I spent $4300 for new PRC heads and I didn't check the condition of the valve guides before hand. Why???? Because it makes me feel better about taking my Z06 on 2,000-3,500 miles trips or just a 90 mile cruise for lunch.
I don't think that much about spending $4,300 on a vacation, that also only makes me feel better, so why would I worry about spending $4,300 for new heads. With the new heads, I actually might even get more for my money over just feeling good. I might just save $15,000 for a new engine in the future.
I don't think that much about spending $4,300 on a vacation, that also only makes me feel better, so why would I worry about spending $4,300 for new heads. With the new heads, I actually might even get more for my money over just feeling good. I might just save $15,000 for a new engine in the future.
11-17-2013, 09:30 AM
#17
Le Mans Master
I'm having the wiggle test done soon. What gets replaced if they are out of spec, the valves or guides?
11-17-2013, 10:33 AM
#19
The images below show what happened to hoefi's valve stems after they had been running in out of spec guides.
Moral of the story: Don't accept any "fix" which would re use exhaust valves which have been running in out of spec guides.
Replace them both.
http://forums.corvetteforum.com/1577942824-post1.html
After 20 months, GM decided it will be too costly to go to trial and decided not to contest my claim fours days before the trial day. In some ways, I feel bad that it didn’t make it to trial because it would have established if the court agrees with GM that a track day is considered racing and thus warrantee repair can be denied. GM originally denied my warrantee based on not finding any defective material or workmanship. Then, shortly after I filed my claim in court, and my subsequent submission of my engineering report as evidence, GM changed their position and focused on my track day usage as their argument.
For detail background information on how this all started, http://forums.corvetteforum.com/c6-z...-warranty.html
....
The major thing that stood out during my investigation is the extreme wear in the exhaust valve guides. I believe I am the first person to report valve guide wear on this forum. Looking at the broken valve stem, it is pretty obvious that it had an overheating problem. Discoloration and significant material transfer is very evident.
[IMG]
[/IMG]
GM’s hired independent outside engineer noted in his investigation report the same observation (see photo below).
[IMG]
[/IMG]
I was looking forward to cross examine this engineer on why he didn’t measure the valve guide when there is galling shown on the valve stem. It should have been the next logical step. Too bad I didn’t get the chance to do that. Besides the broken valve, there is another valve stem (cylinder #5) which shows a small amount of material transfer, indicating the on set of galling (see photo below).
[IMG]
[/IMG]....
For detail background information on how this all started, http://forums.corvetteforum.com/c6-z...-warranty.html
....
The major thing that stood out during my investigation is the extreme wear in the exhaust valve guides. I believe I am the first person to report valve guide wear on this forum. Looking at the broken valve stem, it is pretty obvious that it had an overheating problem. Discoloration and significant material transfer is very evident.
[IMG]
[/IMG]GM’s hired independent outside engineer noted in his investigation report the same observation (see photo below).
[IMG]
[/IMG] I was looking forward to cross examine this engineer on why he didn’t measure the valve guide when there is galling shown on the valve stem. It should have been the next logical step. Too bad I didn’t get the chance to do that. Besides the broken valve, there is another valve stem (cylinder #5) which shows a small amount of material transfer, indicating the on set of galling (see photo below).
[IMG]
[/IMG]....Last edited by '06 Quicksilver Z06; 11-17-2013 at 10:41 AM.