162K on my ‘07 Z06. The heads have never been inspected. My initial thinking was there’s no way it could run for that many miles out of spec, but the more I’ve researched it the more I think I should check them.
Jason's Garage It runs fine. I’ve put 5K miles on it since I bought it from the original owner in December. The guy did zero maintenance other than oil changes. I just replaced the original air filter and cabin filter the other day. I had a scare a couple of weeks back when one of the original spark plugs died.
It's absolutely possible that a Z can run that many miles on stock heads, even if the valves were out of spec. The main issue is HOW MUCH they were out of spec from the factory. If not much, then their lives would be greatly extended because the "wiggling" they do with each stroke would be much less, which means less wear. If another Z has a more-out-of-spec guide, meaning the concentricity of the guide is off more, then it may only last, say, 5000 miles before it drops and grenades the LS7. That's what is so frustrating with this issue. There is NO consistency or quality control with those guides from the vendor that GM used. Sucks for all of us. It's a guessing game and a waiting game; basically a $17,500 gamble in the long run.
@@MugelloZ06 Did you actually pay attention the video? I made it clear that I did the quick visual wiggle test but I sent them to Kohle at AHP and he put a gauge on it. The numbers shown are the actual numbers from that gauge as I moved each valve. I don't do any sort of lame clickbait like half of the other automotive video makers out there. What is in the title is accurate to the content of the video. At 9k miles, almost all of my valves were out of spec. Yes, that is bad news indeed.
My 2007 z06 had heads fixed at 7200 miles and I am currently at 10,200 miles. It passed the “wiggle test” from a corvette race shop who does great work and I got them fixed anyway. This is what they did. Bronze valve guides, solid stem exhaust valves, and Comp cams trunioun upgrade kit. Car is otherwise stock and runs good. My question is what about the Intake valves? I know “the fix” may not be 100% bullet proof on any ls7 due to a geometry problem with the ls7 in general according to the performance shop who did the work. Although with this fix they did say they have never seen one come back and they did this fix on many ls7s. Your thoughts on my set up for the “fix”? Should I sleep easy at night? Car has been solid since fix, 3k miles.
Fixed is such a vague term. A solid exhaust valve stem would fix the problem being the valve breaking in half and falling in the cylinder. Even with the valve not seating right a solid valve wouldn't fail and know one has even found this to be the actual reason and would be easily seen!. Performance engines with large 7000 rpm cams stock just are not going to have long lasting valve trains period. Most should do 50000 miles easy but springs should be changed every 15-20 thousand miles. The Chevy hollow exhaust valves were an accident waiting to happen. Better stronger springs (for high rpm) and heavier solid exhaust valves should have been used. Valve runout is not the end of the world till its wearing into a hollow valve stem breaking it because of it's thin wall specs. Seems like a lot of the bigger hollow ls7 exhaust valves are the main problem. There are loads of ls7's out there with over 75000 miles running fine untouched but you know they have at least some .025 -.040 wobbly valves in them and there valves keep on ticking. GM says less than 5% failed during warrantee. Three year 30000 miles? That kind of tells the story. Your 10000 mile heads would have gotten you to at least 25000 miles unless you fell into the 5%. Some of those exhaust valves must have been made with out of round wall thicknesses and or poor metal strength and some were and are pretty good.
The biggest problem on the intake side is the Titanium material that the intake valves are made of. Titanium HATES other materials. I had AHP rework my LS7 heads, and I'm going with hollow stem Ferrea f2014p stainless intake valves. Heavier than Titanium? Sure are. Longer lasting? ABSOLUTELY. I'll be damned if my $130.00 apiece Titanium valves will be replaced for over a grand, and then reinstall the problem. I've already seen tumble polished Titanium valves wear out brand new bronze valveguides. Titanium is great for all out racing engines. My street driven Vette doesn't see 7,000rpm more than once or twice a month, not hours at a time like a road racer.....
I'd love to see some of these "fixed heads" tested after 20k or so... I need to do my heads on my 57k Z06, but part of me wonders if they are ever truly fixed?!?!?!
A lot of people wonder the same, including myself. Some think that fixing the valves is only part of the problem and there is an overall issue with the valve geometry. I hope that's not true. :) There's been a lot of reworked heads out there, and there's not a ton of failures that I have heard about so far myself, but time will tell.
That's my fear! IDK if it's the offset rocker that causes unusual sideloads or what, but I do lean towards thinking that "fixing" the valve guilds is likely just resetting the clock on these things... I need to pull the rockers off on mine at some point and see how they feel, but there's little doubt in my mind that I'll find some wear! At this point I feel like I have my head in the sand about the condition of my guilds... Yet I'm afraid to really rev the engine up thinking a valve is going to drop. Likewise, I fear I'll spend $7k redoing everything and the damn things will still wear quickly! It would be nice to have some clear answers about this issue!!!
@@ssoffshore5111 I don't think we will ever know the answers. I mean, it IS a high-performance engine, and not exactly built for longevity. But you cannot be afraid to enjoy it. Check the valves correctly, make a decision on what to do, do it...and enjoy the car.
Don’t buy replacement GM heads. If you have a reputable competent aftermarket specialist like Lingenfelter rebuild your heads with superior aftermarket parts the issue won’t come back.
Just a bad casting or being pressed in. they found the issue and fixed it after finding. it does suck but still a hell of a great engine without that issue.
Jason, I don’t think that’s a proper way to test your heads. I just bought brand new AHP fixed heads with harden guides btr dual springs etc... I moved valves just like you did, and they had some play as well. Does that mean my heads are bad?
Nope, your head's are likely not bad because you are right, that's not the best way to test them. Having a gauge on them is the best way and without the spring, which is why I included the numbers that AHP provided as they tested them correctly.
162K on my ‘07 Z06. The heads have never been inspected. My initial thinking was there’s no way it could run for that many miles out of spec, but the more I’ve researched it the more I think I should check them.
WOW...I think you have the highest mileage Z06 I have heard of. Does it run right? Any misfires? I would definitely check them.
Jason's Garage It runs fine. I’ve put 5K miles on it since I bought it from the original owner in December. The guy did zero maintenance other than oil changes. I just replaced the original air filter and cabin filter the other day. I had a scare a couple of weeks back when one of the original spark plugs died.
It's absolutely possible that a Z can run that many miles on stock heads, even if the valves were out of spec. The main issue is HOW MUCH they were out of spec from the factory. If not much, then their lives would be greatly extended because the "wiggling" they do with each stroke would be much less, which means less wear. If another Z has a more-out-of-spec guide, meaning the concentricity of the guide is off more, then it may only last, say, 5000 miles before it drops and grenades the LS7. That's what is so frustrating with this issue. There is NO consistency or quality control with those guides from the vendor that GM used. Sucks for all of us. It's a guessing game and a waiting game; basically a $17,500 gamble in the long run.
Wiggle test performed like that is inconclusive. This is just FUD to get some clicks.
@@MugelloZ06 Did you actually pay attention the video? I made it clear that I did the quick visual wiggle test but I sent them to Kohle at AHP and he put a gauge on it. The numbers shown are the actual numbers from that gauge as I moved each valve. I don't do any sort of lame clickbait like half of the other automotive video makers out there. What is in the title is accurate to the content of the video. At 9k miles, almost all of my valves were out of spec. Yes, that is bad news indeed.
My 2007 z06 had heads fixed at 7200 miles and I am currently at 10,200 miles. It passed the “wiggle test” from a corvette race shop who does great work and I got them fixed anyway. This is what they did. Bronze valve guides, solid stem exhaust valves, and Comp cams trunioun upgrade kit. Car is otherwise stock and runs good. My question is what about the Intake valves? I know “the fix” may not be 100% bullet proof on any ls7 due to a geometry problem with the ls7 in general according to the performance shop who did the work. Although with this fix they did say they have never seen one come back and they did this fix on many ls7s. Your thoughts on my set up for the “fix”? Should I sleep easy at night? Car has been solid since fix, 3k miles.
Fixed is such a vague term. A solid exhaust valve stem would fix the problem being the valve breaking in half and falling in the cylinder. Even with the valve not seating right a solid valve wouldn't fail and know one has even found this to be the actual reason and would be easily seen!. Performance engines with large 7000 rpm cams stock just are not going to have long lasting valve trains period. Most should do 50000 miles easy but springs should be changed every 15-20 thousand miles. The Chevy hollow exhaust valves were an accident waiting to happen. Better stronger springs (for high rpm) and heavier solid exhaust valves should have been used. Valve runout is not the end of the world till its wearing into a hollow valve stem breaking it because of it's thin wall specs. Seems like a lot of the bigger hollow ls7 exhaust valves are the main problem. There are loads of ls7's out there with over 75000 miles running fine untouched but you know they have at least some .025 -.040 wobbly valves in them and there valves keep on ticking. GM says less than 5% failed during warrantee. Three year 30000 miles? That kind of tells the story. Your 10000 mile heads would have gotten you to at least 25000 miles unless you fell into the 5%. Some of those exhaust valves must have been made with out of round wall thicknesses and or poor metal strength and some were and are pretty good.
The biggest problem on the intake side is the Titanium material that the intake valves are made of. Titanium HATES other materials. I had AHP rework my LS7 heads, and I'm going with hollow stem Ferrea f2014p stainless intake valves. Heavier than Titanium? Sure are. Longer lasting? ABSOLUTELY. I'll be damned if my $130.00 apiece Titanium valves will be replaced for over a grand, and then reinstall the problem. I've already seen tumble polished Titanium valves wear out brand new bronze valveguides. Titanium is great for all out racing engines. My street driven Vette doesn't see 7,000rpm more than once or twice a month, not hours at a time like a road racer.....
Why are you wiggling the the springs. It’s the valve guides that’s the problem
I'd love to see some of these "fixed heads" tested after 20k or so... I need to do my heads on my 57k Z06, but part of me wonders if they are ever truly fixed?!?!?!
A lot of people wonder the same, including myself. Some think that fixing the valves is only part of the problem and there is an overall issue with the valve geometry. I hope that's not true. :) There's been a lot of reworked heads out there, and there's not a ton of failures that I have heard about so far myself, but time will tell.
That's my fear! IDK if it's the offset rocker that causes unusual sideloads or what, but I do lean towards thinking that "fixing" the valve guilds is likely just resetting the clock on these things...
I need to pull the rockers off on mine at some point and see how they feel, but there's little doubt in my mind that I'll find some wear! At this point I feel like I have my head in the sand about the condition of my guilds... Yet I'm afraid to really rev the engine up thinking a valve is going to drop. Likewise, I fear I'll spend $7k redoing everything and the damn things will still wear quickly! It would be nice to have some clear answers about this issue!!!
@@ssoffshore5111 I don't think we will ever know the answers. I mean, it IS a high-performance engine, and not exactly built for longevity. But you cannot be afraid to enjoy it. Check the valves correctly, make a decision on what to do, do it...and enjoy the car.
I hope they are truly fixed. I just replaced my Z28 heads for AHP heads.
How has the fixed heads held up?
Don’t buy replacement GM heads. If you have a reputable competent aftermarket specialist like Lingenfelter rebuild your heads with superior aftermarket parts the issue won’t come back.
Are you removing the sodium filled exhaust valves? Or are they a failure point as well as the guide's. I have same engine at 12k
See this video for everything I did: th-cam.com/video/IjZsagCk-x8/w-d-xo.html
Just a bad casting or being pressed in. they found the issue and fixed it after finding. it does suck but still a hell of a great engine without that issue.
Jason, I don’t think that’s a proper way to test your heads. I just bought brand new AHP fixed heads with harden guides btr dual springs etc... I moved valves just like you did, and they had some play as well. Does that mean my heads are bad?
Nope, your head's are likely not bad because you are right, that's not the best way to test them. Having a gauge on them is the best way and without the spring, which is why I included the numbers that AHP provided as they tested them correctly.
The spring doesn't matter. The STEM shouldn't move more than .002! Newly rebuilt.
Why r you wearing a lingenfelter shirt and not an ahp shirt.
I do have an AHP shirt. Probably should've had it on for this one, but I grabbed whatever was in my drawer that day. :)
I sold my 2009 zo6 to the Chevrolet dealership didn't want to deal with it
I bought my 2009 Z06 knowing this was an issue and that I would have to fix it. I have no regrets myself.
They built them to good before