[quote]Originally posted by spiesscj:
<strong>

The 2002 springs will take more lift than that, the 2002 LS6 cam is 0.551/0.547</strong><hr></blockquote>

I am not certain, but I think the 2002 LS6 valves are lighter than the valves in our cars.

 

Just my 2ct FWIW... I tend to think alot of valve train issues, if set up properly, have to do with improper warm up at initial start. I've seen guys crank their cars and I begin to cringe when I hear them rpm the sh** out of a cold motor. I'm like WTF?! I'm sure ya'll have heard it too and most of the time its the young, inexperienced people that just don't get it. I have always with every "built" motor and even my stock ones wait until a good operating temp before I hammer on them. CinderSS, not saying thats what happened to the 918 in your car. Just something to keep in mind...

 

That is the first one that I have heard of breaking.
As Nick said, he has some very hard miles on his with a VERY agressive cam and his car is running great!

 

Wow, I hope that was a freak spring. <img src="gr_sad.gif" border="0"> I'm installing a .581 cam w/ 918s this weekend.

 

I have about 4000 hard miles on a set of 918s and 772 retainers with a 223/223 .588/.588 cam, and the springs are holding up great.

 

quote:
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Originally posted by spiesscj:

The 2002 springs will take more lift than that, the 2002 LS6 cam is 0.551/0.547


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[quote]Originally posted by Ragtop 99:
<strong>

I am not certain, but I think the 2002 LS6 valves are lighter than the valves in our cars.</strong><hr></blockquote>

Yes the 2002 LS6 valves are significantly (~25%) lighter than standard LS1 valves.

This topic always kind of bothers me when people say that a certain spring is good for "x" amount of lift. There is really 2 issues here. One is how much lift can the spring support before coil bind. This is an absolute limit - if you run a cam with a higher lift, the valve won't close all the way (well maybe the lifters can compensate some, but with a solid roller this would be the absolute limit).

The second issue is while the springs may be able to support "x" amount of lift before coil bind, they may not be able to support slightly below that lift with a certain cam and stock valves at a given rpm.

Rev a stock engine up to 10,000 rpm and see - the stock springs should be able to handle the .500" lift of the stock cam no problem, but revving up the rpms will eventually float the valves.

Cam A and Cam B can have the same maximum lift, but one will float the valves, and the other one won't due to differences the the ramp rates (acceleration) of the lobes.

It all goes back to Newton's F = ma. The force exerted by the valvespring necessary to control valve float is equal to the mass of the valve times the acceleration caused by the camshaft lobes and rpms.

For a given rpm and camshaft profile, lighter valves will require a less stiff spring to control valve float.

You can't say spring 'A' is good for 'x' lift for all combinations of lobe profiles and valve weight. You can state a maximum lift (before coil bind) that a spring is good for.

This is what buqs me. Just because cam A with 'x' amount of lift will work fine with a certain valve spring, doesn't mean cam B with the same maximum lift will work with it.

 

If it is worth anything. I have had th 918 springs in for 16k miles and I have beat the utter crap out of mine. Quite a few top speed runs (extended high RPM) and I bounce the limiter more than I should. They have even been through a nasty miss, 3 to 2. Through all this, they have held up like a champ. Great spring in my opinion.

 

Did you do a heat cycle on them when you put them in?

 

[quote]Originally posted by DJ's99SS:
<strong>Just my 2ct FWIW... I tend to think alot of valve train issues, if set up properly, have to do with improper warm up at initial start. I've seen guys crank their cars and I begin to cringe when I hear them rpm the sh** out of a cold motor. I'm like WTF?! I'm sure ya'll have heard it too and most of the time its the young, inexperienced people that just don't get it. I have always with every "built" motor and even my stock ones wait until a good operating temp before I hammer on them. CinderSS, not saying thats what happened to the 918 in your car. Just something to keep in mind...</strong><hr></blockquote>

This is pretty much what I was thinking. Cinder, did you follow the break in instructions for the springs? If not, spring life will be compromised. I didn't realize this until a couple of days after my cam install, but luckily did the break in procedure without knowing it. Everythings running fine so far with 2k+ miles. .581/.588 lift and many 6600 rpm shifts.

 

Well I removed the spring to test the valve and see if it was bent last night. The valve is fine but the springs are not 918 springs like I was told where put on the car. It turns out I have been running on 941's!! I'm pretty damn mad! Now, not only do I have to buy new springs I also have to buy new retainers. Sorry for the post. I was told many times by the installer of my heads that 918's where on the car. I guess their is only one way to do something, and that's to do it yourself! Again sorry for the post.

 

WHOA! <img src="gr_eek2.gif" border="0"> That sucks! Boy would I be pissed too. At the same time, I'm glad they weren't 918s. Make the shop pay for the new springs and retainers. <img src="gr_sad.gif" border="0">

 

[quote]Originally posted by J'sRamAir:
<strong>WHOA! <img src="gr_eek2.gif" border="0"> That sucks! Boy would I be pissed too. At the same time, I'm glad they weren't 918s. Make the shop pay for the new springs and retainers. <img src="gr_sad.gif" border="0"> </strong><hr></blockquote>
The shop should also replace all of the parts and compensate you for your trouble.

 

holy crap! that sucks make sure thoose bastages pay!! <img src="gr_stretch.gif" border="0"> man that makes me feel a lot better about runnin thoose 918 springs now (wiping sweat from head) <img src="gr_stretch.gif" border="0">

 

That sucks man! (Makes me feel better too though) <img src="gr_stretch.gif" border="0">
I agree, the shop that told you they put in 941s is completely responsible for all the costs.

 

[quote]Originally posted by PewterZ:
<strong>And I have heard of 2 cars breaking 918's on the number 1 cylinder too....weird.</strong><hr></blockquote>

Really?! Can you give us some more info on this, like the cams they were running and what rpm ranges they were revving to? Thanks <img src="gr_stretch.gif" border="0">

 

[quote]Originally posted by mattf2:
<strong>Has anyone installed the ZO6 springs w/ aftermarket cam? I know they're good to 66-6800.</strong><hr></blockquote>

Yeh I did with the GM Hot Cam....Runs Fine....And I have heard of 2 cars breaking 918's on the number 1 cylinder too....weird.

 

[quote]Originally posted by CinderSS:
<strong>Well I removed the spring to test the valve and see if it was bent last night. The valve is fine but the springs are not 918 springs like I was told where put on the car. It turns out I have been running on 941's!! I'm pretty damn mad! Now, not only do I have to buy new springs I also have to buy new retainers. Sorry for the post. I was told many times by the installer of my heads that 918's where on the car. I guess their is only one way to do something, and that's to do it yourself! Again sorry for the post.</strong><hr></blockquote>


Wow, Sorry for your trouble!! <img src="gr_sad.gif" border="0"> A lot of people including myself are sure glad it wasn't a 918 though!! <img src="gr_stretch.gif" border="0">