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I've got an LS7 that has sat for several years waiting for a project car to be finished, and I'm concerned about the valve springs having sat compressed during that time. From what I understand, they are either Comp 921s or PAC 1521 springs, though the engine builder is no longer in business. I took a couple pics trying to find identifying marks, but found none, not that i know what I'm looking for. Any chance anyone here can ID them, either from color or the appearance of the Ti retainers? If there are different angle shots I should take to help the ID process, that won't be a problem.
I think the only real way to ID them would be to pop a couple out and test them.
Get one or more that was "open", and compare to "closed" one(s) to check for degradation.
Just a thought....
If your LS7 has hydraulic lifters, they will have bled down reducing the tension on the valve springs. If the engine has a solid roller cam or low lash solid roller cam they spring would have the full tension on them.
I think of it like this valve springs are inexpensive and a new set of quality valve springs are great investment.
If they are that old, just get a brand new set.
They are not that expensive and it's good insurance.
No way I would run a set of springs compressed for years.
thanks for the input gents. I assume using a spring install checker is the only way to ensure that a set of PAC 1521 gets done correctly. Off-hand, does anybody know what shims are typically included with the spring kit? To the best of my knowledge, the spring perches are stock/not machined. Also, any recs for LS7 spring compressor?
I've got an LS7 that has sat for several years waiting for a project car to be finished, and I'm concerned about the valve springs having sat compressed during that time. From what I understand, they are either Comp 921s or PAC 1521 springs, though the engine builder is no longer in business. I took a couple pics trying to find identifying marks, but found none, not that i know what I'm looking for. Any chance anyone here can ID them, either from color or the appearance of the Ti retainers? If there are different angle shots I should take to help the ID process, that won't be a problem.
TIA,
Tom
Hi Tom. My name is Mike. Back in 2005-2006, I ran some AFR 225 heads that had 921 Comp springs. They were some of the 1st AFR 225s around, and someone at AFR screwed up by setting them at a 1.700 installed height, instead of 1.770!!! This was due to a faulty metric to SAE math conversion by the head assembler at AFR. I ran those springs for 30,000 miles shimmied almost a hundred thou too stiff!! Never broke a spring. They may be expensive, but they are a HELLUVA spring! I dont believe they would be damaged for street, occasional strip use. Sure, if you're trying to set a national record in NHRA competition, I'd at least check them, or replace them. I think you'd be good to go as is. Why not call Comp? Just remember, they're in business to sell products, so you'll have to consider that too. In Michigan, our cars sit for 6 months, or more, every year. I've never met anyone who said their Springs sagged because they didn't drive their car last year. Lots of people will want you to spend YOUR money. I'd call Comp, then get it running to see if there's any problem. I think LS7 heads have many more serious valvetrain issues than Springs that have been compressed for a couple years! Just my .02.......
The retainers look like the PAC I just installed. They fit a lot of diff PAC springs.
Might be a clue.
I agree. They look like PAC retainers. Mine new retainers have the PAC name etched/inkmarked on the top of them. Was at PAC yesterday having them ID my springs and retainer. They told me I have PAC 1908 dual springs and their tool steel retainer. After they concluded the springs and retainers were indeed already PAC items, I bought the appropriate titanium retainers to fit the 1908 duals.
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help IDing valve springs 
