[Z06] 02 Z06 valve spring broken. Another one bites the dust
04-14-2010, 05:41 PM
#21
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Those look like Comp 921 dual springs to me. If so it looks like the inner spring saved you from dropping the valve.
If it was me, I would pull the spark plug and see if there is any damage to it. If you have a bore-scope poke your eye inside the cylinder and see if there is any damage to the piston. If it did break and you had some high RPM use with it, it might have touched the piston and bent the valve. If that is the case the head is going to have to come off and the valve replaced.
You might have dodged it and just need springs.
But those are not 918's for sure. Figure out what cam is in it before buying springs so you know they will work with it.
If it was me, I would pull the spark plug and see if there is any damage to it. If you have a bore-scope poke your eye inside the cylinder and see if there is any damage to the piston. If it did break and you had some high RPM use with it, it might have touched the piston and bent the valve. If that is the case the head is going to have to come off and the valve replaced.
You might have dodged it and just need springs.
But those are not 918's for sure. Figure out what cam is in it before buying springs so you know they will work with it.
04-14-2010, 06:57 PM
#22
Racer
Those look like Comp 921 dual springs to me. If so it looks like the inner spring saved you from dropping the valve.
If it was me, I would pull the spark plug and see if there is any damage to it. If you have a bore-scope poke your eye inside the cylinder and see if there is any damage to the piston. If it did break and you had some high RPM use with it, it might have touched the piston and bent the valve. If that is the case the head is going to have to come off and the valve replaced.
You might have dodged it and just need springs.
But those are not 918's for sure. Figure out what cam is in it before buying springs so you know they will work with it.
If it was me, I would pull the spark plug and see if there is any damage to it. If you have a bore-scope poke your eye inside the cylinder and see if there is any damage to the piston. If it did break and you had some high RPM use with it, it might have touched the piston and bent the valve. If that is the case the head is going to have to come off and the valve replaced.
You might have dodged it and just need springs.
But those are not 918's for sure. Figure out what cam is in it before buying springs so you know they will work with it.
I'm gonna bite the bullet and do some dual springs in my 40K mile 02Z pretty soon.
Anthony@LG, you have PM
04-14-2010, 07:04 PM
#24
Race Director
Just read Anthony's input....921s?? Wow, they're really $$$$ parts. Optional upgrade on AFR heads, IIRC.
Last edited by zeevette; 04-14-2010 at 07:07 PM. Reason: Just read add'l posts
04-14-2010, 07:21 PM
#25
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
Yeah, I know those are Dbls, that's what saved the day, methinks. The 918 thing sounds familiar, now that you mention it... a single spring. Still, it's interesting what caused a DBL to break in a non- competition setting, just like the stock ones. I sure don't remember hearing of anybody breaking an aftermarket DBL just street driving.
Just read Anthony's input....921s?? Wow, they're really $$$$ parts. Optional upgrade on AFR heads, IIRC.
Just read Anthony's input....921s?? Wow, they're really $$$$ parts. Optional upgrade on AFR heads, IIRC.
Also depends on how big the cam is, bigger cams are going to wear the springs out even in normal street driving you may have to do a spring change every 30k miles or so.
Guys that regularly track the cars, they do springs once a year. It's cheap insurance if you have ever had to pull a valve head out of a piston.
04-14-2010, 07:24 PM
#26
Depends on what it is. If it is one of our cam kits, then there is a 99.9% chance it has 921's on it.
Also depends on how big the cam is, bigger cams are going to wear the springs out even in normal street driving you may have to do a spring change every 30k miles or so.
Guys that regularly track the cars, they do springs once a year. It's cheap insurance if you have ever had to pull a valve head out of a piston.
Also depends on how big the cam is, bigger cams are going to wear the springs out even in normal street driving you may have to do a spring change every 30k miles or so.
Guys that regularly track the cars, they do springs once a year. It's cheap insurance if you have ever had to pull a valve head out of a piston.
Do you guys track installs by VIN that you may have done? This car came out of Texas.
04-14-2010, 07:48 PM
#28
Race Director
Well I'm posting some pics below for everyones enjoyment. I have about 34,000 miles on the car right now and it is cammed. I am not sure if a cam kit was installed with the cam because the person I bought the vette from also bought it that way and he didn't know anything. Are the stock LS6 springs supposed to be yellow? Mine isn't so I'm not sure if they are stock or aftermarket.
The valve hasn't dropped so I'm crossing my fingers and waiting on a friend to see if they can get a bore scope to examine the piston. I'm also trying to find a modified valve spring compressor at the moment.
Thanks for all the responses so far..
Spencer
The valve hasn't dropped so I'm crossing my fingers and waiting on a friend to see if they can get a bore scope to examine the piston. I'm also trying to find a modified valve spring compressor at the moment.
Thanks for all the responses so far..
Spencer
Damm few things strike fear in the heart of a z06 owner like seeing that under a valve cover.
04-14-2010, 08:09 PM
#32
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04-14-2010, 08:29 PM
#34
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Valve springs have what is called installed height/closed spring pressure, and open/max lift pressure. meaning the valve is full open.
when you get a new cam they give you card about closed pressure settings and you shim it to get that pressure, and open press is engineered to match the cam, you have a large tool you hook on the rocker stud and pull back on it, it has a dial that measures resistance..thus giving you readings of closed pressure and open pressures...kinda hard to tell you all this typing, I am probably not getting the point across very well, try youtube there may be a good vid on installing springs properly?.
bottom line, all springs are diff for diff styles of cams, Solid, Hyd, Roller, and how radical of lifts they have, there job is to hold the lifter tight to the cam and it takes press to get it done, so you really need to know what you have exactly.
B.
when you get a new cam they give you card about closed pressure settings and you shim it to get that pressure, and open press is engineered to match the cam, you have a large tool you hook on the rocker stud and pull back on it, it has a dial that measures resistance..thus giving you readings of closed pressure and open pressures...kinda hard to tell you all this typing, I am probably not getting the point across very well, try youtube there may be a good vid on installing springs properly?.
bottom line, all springs are diff for diff styles of cams, Solid, Hyd, Roller, and how radical of lifts they have, there job is to hold the lifter tight to the cam and it takes press to get it done, so you really need to know what you have exactly.
B.
04-14-2010, 08:49 PM
#35
Racer
04-15-2010, 10:36 AM
#38
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St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13
On the bigger and more aggressive cams duals are nice encase something like this happens because you can save a valve if one of the two springs break and you catch it in time.
04-15-2010, 12:44 PM
#39
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Again....read above. You need to get a spring for the cam that is in the car. 921 duals are WAY overkill for a stock cam and would probably do more harm than good.
On the bigger and more aggressive cams duals are nice encase something like this happens because you can save a valve if one of the two springs break and you catch it in time.
On the bigger and more aggressive cams duals are nice encase something like this happens because you can save a valve if one of the two springs break and you catch it in time.
i remember you posted about your car making low power cammed with not a clue on the cam...too bad you couldnt find out what cam is in it...does it have a lot of lope? could be a sleeper cam with short durations aggressive lobes with lots of lift and you have insuffienct springs...put some PRC EHT .675s in it and go on with life! where did it peak at and do you have dyno graph to show how stable it looks at high rpm?
04-15-2010, 02:01 PM
#40
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Again....read above. You need to get a spring for the cam that is in the car. 921 duals are WAY overkill for a stock cam and would probably do more harm than good.
On the bigger and more aggressive cams duals are nice encase something like this happens because you can save a valve if one of the two springs break and you catch it in time.
On the bigger and more aggressive cams duals are nice encase something like this happens because you can save a valve if one of the two springs break and you catch it in time.