Replacing LS6 Valve Springs
Thread Starter
Instructor
Joined: Feb 2006
Posts: 143
Likes: 4
From: Wichita KS
Replacing LS6 Valve Springs
I posted this under the Z06 Section, but this is probably the more appropriate section.
I have become paranoid with the accounts of broken valve springs on the LS6. I have decided that I am going to replace mine for peace of mind. I know that the chances of breaking a spring are low, but it is happening more than I am comfortable with, so i have decided to go ahead and upgrade the springs. My car is an early 2002 build, but from what I have seen and read, broken springs have occured on 2002, 2003, and 2004 models. It is bone stock. Than being said, I think I have decided on the PAC 1518 nitrated spring, but the spring rate is 313 lb/in vs. the stock rate of 271 lb/in. I know this is probably overkill, but I don't want to worry about this again for a long time.
Because of the higher spring rate, should I also change my pushrods to something stronger? If so, any recomendations on hardened pushrods that are as light or lighter than the stock ones?
Any other things that I should change?
Thanks.
Steve
I have become paranoid with the accounts of broken valve springs on the LS6. I have decided that I am going to replace mine for peace of mind. I know that the chances of breaking a spring are low, but it is happening more than I am comfortable with, so i have decided to go ahead and upgrade the springs. My car is an early 2002 build, but from what I have seen and read, broken springs have occured on 2002, 2003, and 2004 models. It is bone stock. Than being said, I think I have decided on the PAC 1518 nitrated spring, but the spring rate is 313 lb/in vs. the stock rate of 271 lb/in. I know this is probably overkill, but I don't want to worry about this again for a long time.
Because of the higher spring rate, should I also change my pushrods to something stronger? If so, any recomendations on hardened pushrods that are as light or lighter than the stock ones?
Any other things that I should change?
Thanks.
Steve
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
Don't worry about weight on the lifter side, i.e., pushrod weight won't mean diddly. The spring rate won't be the bigger factor, it will be the seat value as the 1518's will set up with higher seat forces. You will likely end up with a seat value around 130 or so, compared to around 100 stock. If you want to use aftermarket pushrods, remember the 7.400" are actually longer than stock but should still work OK.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
You could try the Comp 26915 conical spring. They are designed specifically for the lS1/6. They would give a little less open pressure than the stockers, but are rated to .560 lift.
Comp also has the 26918, with higher seat loads and higher lift capability, but you probably don't really need that one. There were some issues with the early -918's I think, but none reported for the last few years. I have the -915's with a mild cam: only 15k miles, but no problems.
I think the specs for the stock springs and the Comps are as follows.
These would apply to the stock Z06 cam application - 0.550 lift:
'02-'04 Z seat 90 open 294 rate 370 lb/in
Comp-915 seat 105 open 277 rate 313 lb/in
Comp-918 seat 130 open 302 rate 313 lb/in
I didn't look up the PAC springs you mentioned, but if they are dual springs, then they would offer that extra safety you might want.
If they seat at 130 with a 313 rate, they would match the Comp 918 exactly. Many of the guys here run the -918's with stock valvetrain and much more aggressive cams than the stocker, so any of the springs discussed here should be fine with stock valvetrain components on your stock engine.
DG
Comp also has the 26918, with higher seat loads and higher lift capability, but you probably don't really need that one. There were some issues with the early -918's I think, but none reported for the last few years. I have the -915's with a mild cam: only 15k miles, but no problems.
I think the specs for the stock springs and the Comps are as follows.
These would apply to the stock Z06 cam application - 0.550 lift:
'02-'04 Z seat 90 open 294 rate 370 lb/in
Comp-915 seat 105 open 277 rate 313 lb/in
Comp-918 seat 130 open 302 rate 313 lb/in
I didn't look up the PAC springs you mentioned, but if they are dual springs, then they would offer that extra safety you might want.
If they seat at 130 with a 313 rate, they would match the Comp 918 exactly. Many of the guys here run the -918's with stock valvetrain and much more aggressive cams than the stocker, so any of the springs discussed here should be fine with stock valvetrain components on your stock engine.
DG
Thread Starter
Instructor
Joined: Feb 2006
Posts: 143
Likes: 4
From: Wichita KS
Thanks for your input, DG.
The PAC 1518 are a nitrided vesion of their 1218, which is comperable to the Comp 918 beehive design (from what I have found out, PAC originally supplied the 918 spring to Comp). The only reason that I was looking at the PAC springs was based on the few 918 issues I have heard about.
The PAC 1518 are a nitrided vesion of their 1218, which is comperable to the Comp 918 beehive design (from what I have found out, PAC originally supplied the 918 spring to Comp). The only reason that I was looking at the PAC springs was based on the few 918 issues I have heard about.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Vettnuts, yeah, I read something by some guy named Smokey Yunick that said the lifter/pushrod side of the rocker was not weight-critical, the valve/spring/retainer side was where the weight really mattered.
I suppose we can take that to the bank.
DG
I suppose we can take that to the bank.
DG
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