[Z06] Question about the valve drop issue some of the LS7 motors are having
10-27-2011, 12:12 AM
#1
Melting Slicks
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Question about the valve drop issue some of the LS7 motors are having
hey gang,
I know there has been a slew of reports regarding Z06 owners blowing their motors due to valve dropping. I am in the process of buying a used Z06 with the intent of installing a mild 220s or 230s cam in the motor.
Is there any sort of mod that can be done on the valve train components as a safety net so this issue does not arise? I heard replacing the rocker arm trunions would alleviate the problem.
I know there has been a slew of reports regarding Z06 owners blowing their motors due to valve dropping. I am in the process of buying a used Z06 with the intent of installing a mild 220s or 230s cam in the motor.
Is there any sort of mod that can be done on the valve train components as a safety net so this issue does not arise? I heard replacing the rocker arm trunions would alleviate the problem.
Last edited by uracowman; 10-27-2011 at 12:15 AM.
10-27-2011, 12:25 AM
#2
Team Owner
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St. Jude Donor '06
The "Search" feature on this sight is your friend best of luck, you have many, many hours on this very subject you can read up on right at your disposal on this forum.
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
Last edited by Mopar Jimmy; 10-27-2011 at 12:54 AM.
10-27-2011, 01:02 AM
#3
Melting Slicks
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St. Jude Donor '12
I just went with a comp cams 231 247 cam in my 06z. while doing the cam I got spooked by all the threads about the valve problems. I decided to pull the heads and change the guides to be safe. while the heads were off I had .040 shaved off to bump comp for a little more power. I also had the heads ported. while the work was being done the machine shop calls and says the guides were bad and the exhaust valves were shot and needed to be replaced due to excessive wear. this very well may have saved my motor. if you are doing a cam I would do the heads as well. you will get more power and you may prevent a failure at the same time.
Last edited by 2000FRCZ19; 10-27-2011 at 01:05 AM.
10-27-2011, 01:14 AM
#4
Safety Car
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The "Search" feature on this sight is your friend best of luck, you have many, many hours on this very subject you can read up on right at your disposal on this forum.
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
10-27-2011, 04:38 AM
#5
Le Mans Master
I just went with a comp cams 231 247 cam in my 06z. while doing the cam I got spooked by all the threads about the valve problems. I decided to pull the heads and change the guides to be safe. while the heads were off I had .040 shaved off to bump comp for a little more power. I also had the heads ported. while the work was being done the machine shop calls and says the guides were bad and the exhaust valves were shot and needed to be replaced due to excessive wear. this very well may have saved my motor. if you are doing a cam I would do the heads as well. you will get more power and you may prevent a failure at the same time.
10-27-2011, 10:59 AM
#6
Melting Slicks
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The "Search" feature on this sight is your friend best of luck, you have many, many hours on this very subject you can read up on right at your disposal on this forum.
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
Because these threads are becoming WAY to repetitive and redundant and I am tired of repeating myself, that is the best advice I can give you.
Oh yeah, the bad news is after reading about 100 hours on this topic you will find out there is no definitive answer to your question!
I just went with a comp cams 231 247 cam in my 06z. while doing the cam I got spooked by all the threads about the valve problems. I decided to pull the heads and change the guides to be safe. while the heads were off I had .040 shaved off to bump comp for a little more power. I also had the heads ported. while the work was being done the machine shop calls and says the guides were bad and the exhaust valves were shot and needed to be replaced due to excessive wear. this very well may have saved my motor. if you are doing a cam I would do the heads as well. you will get more power and you may prevent a failure at the same time.
Some other input from others would be much appreciated on the topic.
10-27-2011, 11:34 AM
#7
Safety Car
If it still has a warranty from GM, leave it alone until it expires. If you can get an aftermarket warranty to cover the engine, I'd do that.
If you are spending the cash for a cam and tune, I've gathered through reading that you might as well pull the heads and have the valve guides replaced with bronze, a 3 angle valve job, and the exhaust valves at a minimum upgraded. You could have the heads ported as well if you trust the shop doing the work.
The valves not seating properly has been a relevant theory that could explain what's happening.
The rocker arm upgrades will prevent a rocker arm from failing and keep needle bearings out of your oil pan, but this doesn't appear to have any relationship to the valves dropping. And you are just as likely to get a bad rocker aftermarket as you are from GM, unless you are in the Jan - Jun 07 build date range.
This is all opinion and your mileage may vary.
If you are spending the cash for a cam and tune, I've gathered through reading that you might as well pull the heads and have the valve guides replaced with bronze, a 3 angle valve job, and the exhaust valves at a minimum upgraded. You could have the heads ported as well if you trust the shop doing the work.
The valves not seating properly has been a relevant theory that could explain what's happening.
The rocker arm upgrades will prevent a rocker arm from failing and keep needle bearings out of your oil pan, but this doesn't appear to have any relationship to the valves dropping. And you are just as likely to get a bad rocker aftermarket as you are from GM, unless you are in the Jan - Jun 07 build date range.
This is all opinion and your mileage may vary.
Last edited by jedblanks; 10-27-2011 at 11:37 AM.
10-27-2011, 01:01 PM
#9
Melting Slicks
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St. Jude Donor '12
yea. I did a search for a good two hours yesterday and solutions vary from trunions to replacing the rockers to replacing the guides.
at minimum, I am replacing the springs and pushrods. I noticed yesterday that some members were recommending changing out the valves while other members did not agree with the idea.
Some other input from others would be much appreciated on the topic.
at minimum, I am replacing the springs and pushrods. I noticed yesterday that some members were recommending changing out the valves while other members did not agree with the idea.
Some other input from others would be much appreciated on the topic.
10-27-2011, 01:35 PM
#10
Racer
moor failure
Oops the sky is falling again. You guys need to get a life. Enjoy what you have and don't worry what might or not might happen and deal with it if it happens......Mike
10-27-2011, 01:48 PM
#11
Le Mans Master
hey gang,
I know there has been a slew of reports regarding Z06 owners blowing their motors due to valve dropping. I am in the process of buying a used Z06 with the intent of installing a mild 220s or 230s cam in the motor.
Is there any sort of mod that can be done on the valve train components as a safety net so this issue does not arise? I heard replacing the rocker arm trunions would alleviate the problem.
I know there has been a slew of reports regarding Z06 owners blowing their motors due to valve dropping. I am in the process of buying a used Z06 with the intent of installing a mild 220s or 230s cam in the motor.
Is there any sort of mod that can be done on the valve train components as a safety net so this issue does not arise? I heard replacing the rocker arm trunions would alleviate the problem.
10-27-2011, 02:22 PM
#12
Melting Slicks
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St. Jude Donor '12
10-27-2011, 02:40 PM
#13
Burning Brakes
10-27-2011, 02:43 PM
#14
Burning Brakes
oh excuse me for being a free thinker, not sticking my head in the sand, and pretending the mighty ls7 is unbreakable. i would rather spend $2000 in head work and save a $14000 engine than run it as is till it breaks. in my case it would not have been long due to the excessive wear on the valves and guides with the higher lift cam. if you are doing a cam you might as well do it especially if you dont know the history of the car. my car had 55000 miles on it when it went in for the work. i am not upset about the issue because it turned out well for me. i dont feel all ls7s are going to drop an exhaust valve, but if it is going to be tracked or modded with an agressive cam then i think its worth doing the heads unless you have excessive funding and $14000 is nothing to your wallet. if i were not modding the car or it never sees track time then i dont think i would have pulled the heads. i would have just drivien it till it broke. who knows how long it would have lasted that way. i have had performance engines that did wear guides in the past and i found it to be acceptable for the power they made and the cam profiles that were used. i love my car and would not trade it for anything else. these are truly amazing machines for the money. i figure if i can do something to prevent a failure in a known problem area i might as well. i would rather drive the thing and enjoy it rather than ignore a potential problem and not be able to drive it because i stuck my head in the sand. i am glad i listend to the all the sky is falling people. it saved me a lot of headache and a lot more cash. if i followed your advice i would be picking up engine parts in a few months.
10-27-2011, 02:52 PM
#15
oh excuse me for being a free thinker, not sticking my head in the sand, and pretending the mighty ls7 is unbreakable. i would rather spend $2000 in head work and save a $14000 engine than run it as is till it breaks. in my case it would not have been long due to the excessive wear on the valves and guides with the higher lift cam. if you are doing a cam you might as well do it especially if you dont know the history of the car. my car had 55000 miles on it when it went in for the work. i am not upset about the issue because it turned out well for me. i dont feel all ls7s are going to drop an exhaust valve, but if it is going to be tracked or modded with an agressive cam then i think its worth doing the heads unless you have excessive funding and $14000 is nothing to your wallet. if i were not modding the car or it never sees track time then i dont think i would have pulled the heads. i would have just drivien it till it broke. who knows how long it would have lasted that way. i have had performance engines that did wear guides in the past and i found it to be acceptable for the power they made and the cam profiles that were used. i love my car and would not trade it for anything else. these are truly amazing machines for the money. i figure if i can do something to prevent a failure in a known problem area i might as well. i would rather drive the thing and enjoy it rather than ignore a potential problem and not be able to drive it because i stuck my head in the sand. i am glad i listend to the all the sky is falling people. it saved me a lot of headache and a lot more cash. if i followed your advice i would be picking up engine parts in a few months.
I agree somewhat even though I am not tracking the car, and didnt upgrade the cam; I did the bronze guides, ss exhaust vales, upgraded springs, and new OEM rockers with Harland sharps upgrade, just to be safe.
10-27-2011, 03:01 PM
#16
Safety Car
Did you port the heads at all? Thinking about doing a similar setup
10-27-2011, 03:44 PM
#17
Melting Slicks
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St. Jude Donor '12
Just curious if your engine builder recommended shaft mount rockers for your cam, to help with geometry? I have the same cam (I think) - mine is ground on a 113 LSA, with ~ 0.640" lift. The high lift associated with the guide concerns makes me wonder if shaft mounts help alleviate this at all.
10-27-2011, 10:20 PM
#19
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St. Jude Donor '06
I bet some of you guys don't realize that LS7 Heads come Cnd'd ported from the factory, really not a lot to gain there, but milling the heads is the winning ticket to extract that little extra horsepower (lying within those very high performing/flowing stock LS7 heads). 
Mill the heads to make around 11:8 to compression to hit that 600rwhp mark (with aftermarket cam of course), and do all the other basic stuff that Jason at Katech recommonds if one wants to safe- guard against the dropping valve issue.
1. Bronze Valve Guides.
2. 3 Angle Valve Job
3. Stock TI vales unless your building a real CRAZY high HP motor or a racing engine (625+rhwp) then use Inconel (sp?) valves.
4. If using stock cam STICK with new OEM springs and STOCK rockers. Of course upgrade to proper sping and pushrod if she is cammed up.
!
Mill the heads to make around 11:8 to compression to hit that 600rwhp mark (with aftermarket cam of course), and do all the other basic stuff that Jason at Katech recommonds if one wants to safe- guard against the dropping valve issue.
1. Bronze Valve Guides.
2. 3 Angle Valve Job
3. Stock TI vales unless your building a real CRAZY high HP motor or a racing engine (625+rhwp) then use Inconel (sp?) valves.
4. If using stock cam STICK with new OEM springs and STOCK rockers. Of course upgrade to proper sping and pushrod if she is cammed up.
!
Last edited by Mopar Jimmy; 10-27-2011 at 11:26 PM.
10-27-2011, 10:23 PM
#20
Le Mans Master
I would change the exhaust valves to a quality one piece valve and inspect the exhaust guides for wear. A lot of guides wear and cause the 2 piece exhaust valves to break. This will cause major damage to the engine. Easy driven Z's don't seem to have any problems, Only the ones that are driven hard for the most part have issues of exhaust valve problems.