Potential Valve Spring Fatigue Advice
Thread Starter
Pro
Joined: Apr 2003
Posts: 568
Likes: 12
From: Jacksonville Florida
Potential Valve Spring Fatigue Advice
I'm running a 226/230 cam, looks like an XE-R series cam based on the Comp Cams master lobe index. The lift is .585 and .592 respectively.
The heads are Stage III 862 Castings, using 2.055 Intake and 1.60 exhaust valves. Comp Cams 921 springs were used.
The entire setup was installed by The Vette Doctors, and has been running very well for the past 5 years / 8k miles.
Finally, the question. The XE-R cam series has a pretty aggressive ramp speed for opening and closing the valve. Is there any practical knowledge out there that can give me an idea how often I should change the springs prior to breaking one?
Thanks in advance for the assistance.
The heads are Stage III 862 Castings, using 2.055 Intake and 1.60 exhaust valves. Comp Cams 921 springs were used.
The entire setup was installed by The Vette Doctors, and has been running very well for the past 5 years / 8k miles.
Finally, the question. The XE-R cam series has a pretty aggressive ramp speed for opening and closing the valve. Is there any practical knowledge out there that can give me an idea how often I should change the springs prior to breaking one?
Thanks in advance for the assistance.
Le Mans Master
Joined: May 2007
Posts: 5,393
Likes: 17
From: Belleville Mich.
I'm running a 226/230 cam, looks like an XE-R series cam based on the Comp Cams master lobe index. The lift is .585 and .592 respectively.
The heads are Stage III 862 Castings, using 2.055 Intake and 1.60 exhaust valves. Comp Cams 921 springs were used.
The entire setup was installed by The Vette Doctors, and has been running very well for the past 5 years / 8k miles.
Finally, the question. The XE-R cam series has a pretty aggressive ramp speed for opening and closing the valve. Is there any practical knowledge out there that can give me an idea how often I should change the springs prior to breaking one?
Thanks in advance for the assistance.
The heads are Stage III 862 Castings, using 2.055 Intake and 1.60 exhaust valves. Comp Cams 921 springs were used.
The entire setup was installed by The Vette Doctors, and has been running very well for the past 5 years / 8k miles.
Finally, the question. The XE-R cam series has a pretty aggressive ramp speed for opening and closing the valve. Is there any practical knowledge out there that can give me an idea how often I should change the springs prior to breaking one?
Thanks in advance for the assistance.
Why not replace them with the Comp 921's, that have been doing so well for you & your engine.
Just look at it as cheap maintenance.
Thread Starter
Pro
Joined: Apr 2003
Posts: 568
Likes: 12
From: Jacksonville Florida
Spring Change Recommendation
Can't argue with the recommendation to change them out, but I was hoping for someone with direct experience with a combination similar to mine. An although there has been significant time since the mods, 8k on a set of springs doesn't seem like a lot of wear.
In the time since these mods were done, spring selection may have changed due to lessons learned. I'm on the very front end of the beginning of my LS1 learning curve, and figure that this is most likely a "well plowed field" by my fellow forum members. It's also possible that my concerns are unfounded. My previous experience was with the LT1. Didn't hear the same things in the valve train that our LS1's transmit.
Thanks for chiming in.
In the time since these mods were done, spring selection may have changed due to lessons learned. I'm on the very front end of the beginning of my LS1 learning curve, and figure that this is most likely a "well plowed field" by my fellow forum members. It's also possible that my concerns are unfounded. My previous experience was with the LT1. Didn't hear the same things in the valve train that our LS1's transmit.
Thanks for chiming in.
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Call Vette Doctors and get their input. I hesitate to make recommendations on valve spring life solely because if one fails I wouldn't have wanted to be one who said it was OK.
However, fatigue is a function of number of cycles, not age. The only issue with age is that some are obviously left compressed when the motor is off.
However, fatigue is a function of number of cycles, not age. The only issue with age is that some are obviously left compressed when the motor is off.
Thread Starter
Pro
Joined: Apr 2003
Posts: 568
Likes: 12
From: Jacksonville Florida
Excellent point.
I called the Doctors looking for build specs for the cam and heads, but I'm afraid the work was done too far back for them to have that info readily available. I was too focused on that answer to proceed with asking for their recommendations.
I called the Doctors looking for build specs for the cam and heads, but I'm afraid the work was done too far back for them to have that info readily available. I was too focused on that answer to proceed with asking for their recommendations.
Drifting
Joined: Apr 2009
Posts: 1,898
Likes: 9
From: Morrisville PA
8k miles is low for springs.
If you really want to know, you have to pull a spring and have it tested. Otherwise, you are just shooting in the dark. With that being said, I wouldn't change them at only 8k.
If you really want to know, you have to pull a spring and have it tested. Otherwise, you are just shooting in the dark. With that being said, I wouldn't change them at only 8k.
Premium Supporting Vendor
Joined: Sep 2008
Posts: 134
Likes: 0
8k miles is low for springs but 5 years of use is not in my opinion. What you can do is pull one off and take it to a machine shop to have the spring pressures checked. This will tell you if they are really wearing out or not. Typically we recommend changing out aftermarket springs once every 4 years if they haven't reached a high mileage. On that cam I would expect those to last at least 30,000 miles. So checking the pressure would be best in my opinion, it would let you know where you are at.
Thread Starter
Pro
Joined: Apr 2003
Posts: 568
Likes: 12
From: Jacksonville Florida
8k miles is low for springs but 5 years of use is not in my opinion. What you can do is pull one off and take it to a machine shop to have the spring pressures checked. This will tell you if they are really wearing out or not. Typically we recommend changing out aftermarket springs once every 4 years if they haven't reached a high mileage. On that cam I would expect those to last at least 30,000 miles. So checking the pressure would be best in my opinion, it would let you know where you are at.
That is excellent advice. It sounds obvious once stated, but sadly enough that had not occurred to me.Thanks for the help fellas.
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Le Mans Master
Joined: May 2007
Posts: 5,393
Likes: 17
From: Belleville Mich.
Thread Starter
Pro
Joined: Apr 2003
Posts: 568
Likes: 12
From: Jacksonville Florida
Paying Attention.
I did as he recommended and contacted VD. They felt the new 921 spring from Comp Cams had improvements over the units installed in '07. No elaboration on what that might be.
Their advice was to change them out using the complete kit. Nothing wrong with that guidance, except that it still does not give me any idea what type of ongoing inspection or replacement interval I should maintain.
It's probably not reasonable for me to expect a business to go out on a limb and risk their reputation on a car they no longer maintain, so I'm good with the info they gave. Frankly, I don't know with certainty if there is a fatigue issue to be concerned with. As stated, I'm on the front end of this learning curve.
I do know this, though. There is hands on experience resident within the Forum from guys that drive these cars every day. I'm doing my best to tap in to that.
JohnJ@TexasSpeed, Thanks for the guidance. That is specific info that I can act on. Thanks again for taking the time.
Thanks again to all.
Their advice was to change them out using the complete kit. Nothing wrong with that guidance, except that it still does not give me any idea what type of ongoing inspection or replacement interval I should maintain.
It's probably not reasonable for me to expect a business to go out on a limb and risk their reputation on a car they no longer maintain, so I'm good with the info they gave. Frankly, I don't know with certainty if there is a fatigue issue to be concerned with. As stated, I'm on the front end of this learning curve.
I do know this, though. There is hands on experience resident within the Forum from guys that drive these cars every day. I'm doing my best to tap in to that.
JohnJ@TexasSpeed, Thanks for the guidance. That is specific info that I can act on. Thanks again for taking the time.
Thanks again to all.
Last edited by Da Wiz; Jun 29, 2012 at 11:03 AM. Reason: Forgot to Thank JohnJ