ls6 springs/cam with ls1 heavy valves...
 

Will the ls6 springs be able to control the valves with the ls6 cam inside an ls1 with the stock ls1 heavy valves? I already have the yellow springs on my car and I have no problem swapping a cam in just a few hours, so I wanted to do a budget friendly upgrade to the ls6 cam (I have ported heads already) and shoot for 400+ rwhp. It would only be a $250 swap since I have the springs on the heads already. But now I am starting to think this may not work because I have the stock, heavier valves. Thoughts? I could always put on the $250 psi springs, which work with the stock hardware, but then it would be pointless to swap to the ls6 cam as I'd only be $150 more from a custom cam.

i asked this same question a week ago and was told dont waste my time and to quit being cheap. you could however go to the PAC 1218 springs for about a lot cheaper than 250 bucks.

Ya, actually AI just told me this is the reason GM went with the lighter valves in the z06...

So these springs will have issues controlling the valves at high rpms.

How much are the pac 1218s? Do you use stock hardware with those?

I am so up in the air about my cam, it is not even funny...

3 weeks ago, I was sure I was going with a custom AI grind ( they do great work). But my original goal of the car was reliability/longevity over power. I really enjoy just driving the car with 370 rwhp...it pulls great and idles/drives exactly like it did with 300 rwhp. I know for a fact with an ls6 cam, I will retain those manners.

So then my mind swayed to the ls6 cam...now that I realize I can't run the stock yellow springs (with good reliability/longevity) I would feel dumb spending money on springs and going with just an ls6 cam. So now I am thinking about a custom grind again LOL. So tired of changing my mind.

the pac 1218s can be had for around 150.00 and uses all the stock hardware. if you already have a LS6 cam then keep it. I have the 02 LS6 cam and 01 heads and will be more than happy with the gains they provide.

I do not have the ls6 cam yet...

Right now, I have headers, ls6 intake, and AI ported 799 heads. Car made 370 (about 70 HP increase). But I also have the smallest ls1 cam possibly, which is like a 199/199 and less than .480 lift. So I know I would pick up a pretty good amount of HP just from the ls6 cam and would most likely get 400 rwhp.

AI said they have two grinds that work with stock yellow springs...gonna get some more info about those.

Guys there is nothing wrong with the LS6 yellow springs.

They are fine as long as you don't install them on a cam larger then what is used on a 2002 + C5 Z06.

They yellow springs will also work just fine for an LS1 engine with the non-sodium filled valves. They are superior to the regular LS1 springs.

I can't see spending for PAC 1218 springs. I was going to spring ( no pun intended ) for the so called mighty PAC 1518 springs, until I started reading threads about them breaking recently.

I don't think the yellow springs will control the heavier LS1 valves to the RPM capability of the 02-04 LS6 cam. If you go this route I would use PAC 1218's or PSI 1511ML's. The PSI's may require some shims to increase the seat value but you would need to determine the installed height to figure this out.

Which LS6 cam do you have, 01 or 02-04? The 01 LS6 did not use the lighter weight valves. The issue is not so much valve weight but valve stem length on the the 02-04 cam equipped LS6s. The valves were made longer in order to compensate for the smaller base circle on the 02-04 cam and maintain the desired lifter pre-load.

would a longer pushrod compensate for that having that longer valve?

I suppose that a longer push rod will restore the lifter's pre-load. I'm sure there is a reason why the designer decided to go with lighter valves with longer stems. It probably had something to do with a desire for increased reliabity and valve train stability at high RPM.

FWIW- GM no longer makes the yellow valve springs. Now they are blue, and I have no idea whether the specifications changed. I know because I ordered some- but shelved them and opted for PAC 1218's.

I know I read a a few articles that said that they wanted to keep the same length pushrods across the board which is why the went with the longer valves. I had seen once that a 7.425 would take up the difference but I dont have enough parts in front of me to mic.

I don't agree. The 01 cam was smaller and I believe had a lower rev limit. The 02-04 cam was larger and had a higher rev limit. This was accomplished with stiffer valve springs and lighter valves. Both are required to control that cam's valve motion at the upper RPM. With the heavier LS1 valves, I don't believe valve control will be maintained at the higher RPM's.

The yellow springs were used on the LS2 equipped GTOs with non-sodium filled valves, however the GTOs had a less aggressive cam, with less lift, similar to the 2001 C5Z06.

So with that said, I will revoke my original response to the OP and admit that I must agree with you vettenuts.


If I was wrong I was wrong. The important thing is to give correct information.
OP spend more and go with at least the PAC 1218s.


The specs below speak for themselves.


LS6 Valve Springs
1.800"" install height @ 90# pressure.
1.250"" @ 295# pressure.


PAC 1218
Beehive LS1 Spring
OD: 1.290"
130 lbs @ 1.800"
318 lbs @ 1.200"
Lift: 0.600"


PAC 1518
Premium Nitrided Beehive LS1 Spring
OD: 1.290"
130 lbs @ 1.800"
337 lbs @ 1.150"
Lift: 0.650"


PSI 1511ML Beehive
O.D. 1.290"
I.D. .630"
Seat Pressure 130lbs@1.800"
Open Pressure 370lbs@1.175"
Rate Lb./In. 384
Max Lift .625"
Coil Bind 1.100"




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I am a huge fan of the PSI springs, although they can be a bit harder to find.

I found a vendor (non-sponsor) that has them listed for $90 less than the PAC1218s. Not sure if they actually have them in stock.

PSI does seem to have a good reputation, I wonder why they are so scarce.



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Knowing what year you have is a very valid point. :yesnod:
LS6 Valve Springs, 2001 is not the same as 2002-2004.

Full Blue springs, part #1256117 are for 2001 only on the LS6.

Full Yellow spring is the new color and part number, 12586484 It is used on:
2002 – 2004 LS6
All LS3
All LS9
2005 – 2007 LS2

Pink Stripe Part# 12589774 for all LS1

Note these are the single spring part numbers. Kits of springs will have a different part number. :cheers:

You do not agree with what? The rev limiter on my 01 was factory set to 6500 RPM, I've had it as high as 6700 RPM when I was autocrossing without valve float, I brought it back down because it did not gain me anything.
I believe most everyone knows that the 02-04 cam has .025" higher lift than the 01 cam, ergo the smaller base circle and longer valve stems. You should have read my comments in post NR 10 before assuming that I don't know what is required to control valve motioin.

To throw a little wrench in the works... GM's latest LS6 replacement spring. They are all blue now, no more yellow.

http://forums.corvetteforum.com/c5-z...s-from-gm.html

http://i287.photobucket.com/albums/l.../sprigs002.jpg


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I decided to just go with a custom grind from AI with the PSI valve springs. It will be a baby cam for sure, as I want stock idle. Can't wait to install it.

We all read and hear alot of things...

http://www.gmhightechperformance.com...ine/index.html

The '01 base circle reduction did not require a change in dimensions of any other valve train part; however, the 405-horse cam was a different story. "I wasn't comfortable reducing base circle that much," Hicks told us, "without compensating for it somehow, because the position of the plunger within the hydraulic lifter is not optimal any more-you're too high in the lifter.

"There's different ways to correct the geometry. The one we selected to minimize the impact on our manufacturing operations was to increase the length of the valve. The valves in the '02 LS6 are 0.6mm longer than the valves in all other Gen III engines."

With .025 inch more intake lift, the same intake duration at "fifty-up" but a little less duration at lash and the same rev limit; something had to be done to the rest of the valve train to keep it in control at high rpm. While the '02 exhaust lobe doesn't have quite the aggressive profile as the intake, it's still got more lift, so something had to be done there, too. The choices GM made were to decrease valve weight and increase valve spring pressure.

2002 LS6 Engine Valves
Not only are '02 LS6 valves...


"With the higher lift, we needed to reduce the mass of the valvetrain or start getting into a float condition," John Juriga commented. "We went to hollow stem intake and exhaust valves, very similar to what we used in the '96 LT4. We pushed the edge with a state-of-the-art 0.8mm wall thickness-very thin stuff. The exhaust stems are sodium-potassium filled." The '01 intake weighed 99 grams but the '02 weighs only 76. The '01 exhaust weighed 86 grams but the '02 exhaust weighs 63 grams. The exhaust stems are filled with a 78 percent potassium/22 percent sodium mix to help cool the valve. "NaK" is unstable and may spontaneously combust when exposed to air with 50 percent or higher humidity. Do not cut open or shorten '02 Z06 exhaust valve stems.

As a result of the more aggressive cam, the valve springs were also changed. "Even with the lighter valves," Juriga said, "we still needed better control because we open and close them very fast. The closed loads are the same-400 Newtons (90 lbs.) on the seat-but the open loads increase from 1150N (259 lbs.) to 1310N (294 lbs.) for both springs."

A bigger cam, lighter valves, stiffer springs-so goes the ruthless pursuit of power. And what's this new camshaft and valve train stuff worth by itself? Jim Hicks: "You can do a direct A/B comparison and there's an easy 8-10 hp there, whether you change the back pressure or not. There are other changes in the '02 package-exhaust system and induction system-which increase the power more. The overall power increased about 20 hp and the cam was half of it. Again, that's because it's a short-duration design with low overlap so it's not really affected that much by back pressure.



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Good choice. :thumbs:


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Thanks :).

I used to be obsessed with max HP and would choose my parts accordingly.

But theres nothing wrong at all with 400 rwhp and stock idle/mpg/drivability/longevity! The beauty of having a very light car.

I hear you, I've been there.

I'm very happy with my pretty much stock 2004 Z06. I like how light weight it is too.

The only thing I've done is install hardened pushrods, new LS6 yellow springs-retainer-keepers, Harlen-Sharp trunion upgrades and maintaince.

The only other thing I plan on doing possibly is a bigger radiator, oil cooler and maybe high output fans to bring the temps down a bit. I know I could program the fans to kick on at a lower temp but I don't want my fans running all the time.



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Yup, the c5z is a stout car already. My dad has one and its just as fast as my FRC. Those gear ratios help out a lot. We did the same thing on his car and got rid of the silver springs for the yellows as well. Good preventative step IMO.

I was in the market for a c5z before I got my FRC, but with my cam/head install experience, I opted for the much cheaper FRC since I knew I would be modding it anyway. Goal from day one was efficiency/reliability over power, so I am sticking to my guns. I was initially going to do just heads only and stay that way, but my year ls1 cam just effing sucks, so I have to swap it now to hit my power goal.

One thing I realized...you always get used to the power, no matter how much. But you NEVER get used to your car NOT leaving you on the side of the road :). That feeling knowing you will get 30 mpg and can drive across the country with no issues never gets old.

That's weird that your Dad's Z06 had silver springs, so did mine with three orange strips.

The modification path you're taking seems to be one that will give you the best of both worlds in terms of power and reliablilty.

Once in a while I like to take road trips, so reliablilty is important.
LOL, getting stuck on the roadside is not something I want to get use to. :crazy:

The spring in the picture above would be the LS6 (2001) spring only. Single spring part number is 12565117.

As stated in my Original Post, the current NEW springs are full yellow and a much better replacement spring compared to the ones it replaces.

Unfortunately, with my last GTO, which made 460, I got both used to the power and sitting stuck on the roadside.

This was all last summer....


1) First the oil pump went (stuck relief valve)
2) Then the clutch went
3) Then the rearend exploded at the track (ok not the cars fault)
4) Then the lifters went and put debris through the motor and took out the cam bearings and the cam.

NOT FUN. I ended up just cutting my losses and sold it to a friend as is then bought my frc. So, that car jaded me a little bit in terms of modding cars to the extreme levels. The lifters going was the worst obviously...which is one of the reasons the first thing I did on the FRC was swap to ls7's and the good ls2 trays.

That gto was perfectly fine (just slow) with boltons only. Going with big ass cams just takes it toll on the valvetrain overtime (not just your springs).

To get factory-engineering answers to all the questions about the various LS1-LS6 valvetrains, just Google "The Ruthless Pursuit of Power - the Sequel" by Hib Halverson. Really informative reading about the development of the '02 LS6.
If I remember correctly, there was advice that using the '02 cam and springs with the heaver valves would lead to stress if the rev limit was not reduced to below 6300 or so.

DG

(sigh) :rolleyes:

12499224 is the new replacement part number.

I can promise you that they no longer make the yellow springs.
The new yellow springs are now painted blue with the newer part number.

I searched every vendor that sells GM parts on and off of the forum. Many of the pictures on various websites show yellow springs. Even vendors on this website will send you the blue springs to replace your old yellow springs.

I ended up buying a new set of yellow springs from a member on LS1tech otherwise I would have used an aftermarket spring.

If you find a brand new set of yellow springs they will be left over stock.



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Man, I'm sorry to hear about all that. What a bummer last summer.

http://www.garagedooropeners.us/240sx/homer_doh.jpg





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Like the link I posted earlier ?
http://www.gmhightechperformance.com...ine/index.html


By the way vettenutts is a mechanical engineer by trade and he knows his stuff.

Here's an example...
http://forums.corvetteforum.com/c5-t...e-pattern.html



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Yeah that's the link - sorry for redundancy.

dG

It's all good, it a great article.

I never run that high anyway so a set of .025 longer pushrods should allow my 01 Z06 heads, 02 Z06 cam, and yellow springs to work.

For what it's worth, I stand corrected on the color. I spoke with the engineer in charge of small block valve springs this morning. He confirmed the current replacement springs as you pointed out are blue. I was using the GM EPC which I believe needs to be updated. Later today I will have a list of most current part numbers and colors of the springs that I will post. :cheers:

That will be very helpful........and find out about that balancer ;)

The 12499224 number is a 'set' of 16 springs from GM Performance Parts.

12565117 is 2001 LS6 spring - discontinued.

12586484 is the 'individual' 2002-2004 LS6 replacement spring from GM Parts. It has been replaced by number 12625033. Can't comment on the color.

I can comment on the color for 12625033, it is Blue.