boostd4

I bought a car with a broken valvespring. I'm changing all the springs and bought PAC 1518's.

The car has GTP stage 2 ported 5.3L heads. I took one of the springs out and it's noticeably shorter (1/4" ?) than the PAC's. Is this normal? Do I need a different set of springs for 5.3L heads?

Thanks!

-Adam

outkast6991

iTrader: (34)

unless somebody altered the 5.3 heads( cut the pockets for a bigger spring) the 1518's should drop right in i believe. maybe the old springs are just that beat up that they settled. were there any shims on the old springs?

massls1guy

iTrader: (9)

My PAC 1218's were taller than the stockers, sounds right to me.

jetlag

iTrader: (32)

Yeah, I was about to say the same thing.

Those springs will drop right in fine.

PREDATOR-Z

And then poeple post "XXX spring failure, WTF"
Guys, there is proper protocol install on every part in a motor.
To install springs properly, you have to install them all at same height. Recommended for Pac 1518s to deliver said lift and pressure capabilities is 1.800 height.
To do that you need a spring micrometer.
It is so easy it is childish.

Now to the OP:
You are asking a question, you know the answer because it was given to you in a previous post, but what you want to hear is "just drop them in".
Then just drop them in !! Will they work, YES. Will they be properly installed, NO
Why, because you did not follow proper procedure and you do not know if they were fitted properly, "You just dropped them in"

There is a difference between doing it right and just slapping stuff together and hope for the best.

slt200mph

iTrader: (42)

Well said sir ...

boostd4

Well... if you want to bitch me out... to be specific, I REPLIED to your "spring micrometer" recommendation with a logic question that seamed reasonable to me:

"If the spring I'm installing is TALLER than the spring coming out, why on earth would a shim it? My concern is that the spring is TALLER, and therefore CLOSER to coil bind. If I shim these taller springs, won't that make them even closer to coil bind than just dropping them in?"

.... you didn't reply. You chose to bicker about GTP head/spec quality.

Nothing personal. Just a newb trying to understand what's going on. If you want to argue about who makes crappy setups and who doesn't when all I was looking for was a simple explanation to my situation, I'll start a thread where people are focused on my question.

That's all.

boostd4

If we want to "teach" and not be "holier than thou" in this thread, perhaps you can explain this to me...

If the valve spring in extended/relaxed form is longer than the length from the spring seat to the retainer, won't it install at whatever height the distance is from the spring seat to the retainer?

I mean, the spring can't pull the valve stem any further out of the hole if the valve face is fully against the seat.

Do we shim because the retainers bend upward or lose their shape? Do the spring seats get beat downward over time and extend that distance? It seams to me if the spring seats are hardenned and the retainers don't lose their shape, the distance between the two should remain constant. If all of the valve springs you're installing are greater than this length when not compressed (obviously they should be), then they should all install to that specific height, no?

Further, if PAC 1518's are meant to be "drop-in" springs, then their recommended install height of 1.800 should be the factory distance between the seat and the retainer on a fully seated valve (or close to it). Is my logic screwed up?

This is my first LS1 (and pushrod V8 for that matter), but far from my first motor build. I'm uneducated on what parts wear to create tolerance problems like this. I've never had to shim any valvesprings on import 4 or 6 cylinders, even running the valvetrain to 9500 rpm.

PREDATOR-Z

To find out your answer, wouldn't it be logical to put a micrometer on and check what would be your installed height?
I did not say "You will have to shim", I said check installed height and if more than 1.800 then shim the difference.
If less then from your measurement you would find out how far from coil bind they are and you can then address that situation.
But no matter how you look at it, you should measure first.

"Holier than thou" if I'm trying to make you understand not to take shortcuts so you install them correctly (on a boost engine to top it off). Man that is like biting the hand that feeds you.
You ask a question, I give you the answer, but because it is not the one you want to hear, I'm dissing you?

Would you prefer me just BSing you like an idiot? Ok "Just slap them in, you'll be fine"

There is nothing wrong in life with seing truth for what it is, yes it is sharp, but isn't that worth the price of good advice?

Here are the specs on the PAC 1518 (note that it says nothing about "just drop them in specs"

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

If they are installed at higher height, they will not have those pressures.

Wait, I'm not done yet. You have aftermarket heads, well grab on to something, because you have to center your geometry (wipe pattern on valve nose tip). That might require shimming the rocker stands.

So now (if done properly) you have:

Springs all installed at proper height (16 checks)
Geometry centered (rocker wipe nice and centered)

But hold on !! it is not over yet

Now you have to mic your pushrod length and determine your lifter preload and "correct" pushrod length.

After all that is done, now you can light a cigar and sit back admiring that you have actualy set the valvetrain correctly and that it will serve you faithfully.

Darn, that is a whole can of worm, isn't it?

On the other hand you can just "drop everything in" and pray (yes pray) that it will work nicely and for a decent amount of time (but don't count on it).

boostd4

Thank you for restating what you've already said.

The information I'm looking for is still not present (or perhaps I answered it myself..)

Is the REASON one would have to shim valvesprings because the spring seat gets beat up and deformed over time?

I DON'T have a boost engine. I have a simple heads and cam car, and a MILD cam at that (<228 duration, <590 lift). These heads have <40,000 miles on them since they were reconditioned/spec'd. My question is, are the valve seats in 5.3L/LS1 heads so fragile, that a mild setup like mine can deform the seats enough to require shims to renew valvespring geometry?

...and please, I'm not asking whether or not I should mic the height. I know that I should. I'm not trying to take any shortcuts. I'm just trying to get a feel for whats common on these engines.

Thimble

iTrader: (2)

I think everyone's point is....Don't worry about the length of the uninstalled spring - it means nothing.

Springs go soft in use, sometimes soft enough to break. Since you had one break, it should be expected the unloaded length of the old springs will be shorter than a brand new spring. The springs do sag!

If you just drop the springs in and install the retainers and locks you "should" be close to the 1.800" install height. Of course you don't know that w/o checking it. It could be 1.850, it could be 1.780"...it varies. The machining of the spring pockets in the head are hopefully consistent (with a few thousands) from one another...but different valves have different lengths, retainers are not all the same, valve jobs sometimes sink the valves deeper, etc, etc. There ARE variables, and that's why all spring data is based off a specified installed height. The uninstalled length does not matter. The spring could be 6" long for all it matters, as long as it is installed at 1.800", then all the other specs should remain accurate, and you will still get full stated lift capacity out of the spring. .

So let's say you do install them, and with a spring mic, find installed height to be 1.830". Adding .030" shim will bring the spring to 1.800". Make sense?

The other common reason for shimming, is to gain seat pressure when you don't absolutely NEED the max lift capacity of the spring. Most advise shimming to w/i .050" of coil bind. This preloads the spring even more, which generally allows it to control the valve even better.

Since this spring at 1.800" installed height can handle .650" lift...if you're running a .610" lift cam, shimming the springs .030"might not be a bad idea, Yes, you cut .030" of lift capacity off the spring, but it was capacity you don't need....but then again, if your actual installed height worked out to be less than 1.800", you need to know that before just sticking shims in.

FWIW, my springs were intentionally setup at 1.770" installed height.


Hope that helps.

boostd4

Thank you, that was very helpful.

Another question... is there a point where shimming the valves on purpose for better valve control eats horsepower?

Does more spring seat pressure = more effort for the motor to push on the spring? Wouldn't the least amount of seat pressure that could still control the valve at high rpm be the most ideal?

My cam is only .589 lift. I bought these PAC 1518's capable of .650 for peace of mind. I could go ahead and shim them all up 0.030 and still have .030 buffer before the rated lift on the springs. My horsepower peaks at 6100rpm (430whp) and by 6800 is at 395whp. If I'm only revving to 6600, would I even benefit from the added seat pressure of shimming them all .030 (of course assuming that they all mic the same 1.8 to start)?

PREDATOR-Z

If they all are 1.800 you do not need to shim. Only shim if above that.
If your heads have 40K miles on them it is a good idea to change the seals as well while you are in there.

boostd4

So which is it?

If I'm going to go out and buy a shim set say from Speed-Inc, and borrow a spring mic, why *wouldn't* I shim them a bit tighter if I have the slack to get better valve control as Thimble noted?

My cam has .589/.589 lift. The PAC 1518's are rated to .650 lift. My next newbish question is, if I get all the springs to 1.8" and THEN shim them all up an additional .030", what exactly do I gain and lose? I've got plenty of spring length/rate to cover .030... in fact I should have twice that.

My question is twofold:

1) By shimming the spring and increasing seat pressure, do I lose a measureable amount of horsepower due to the motor having to push against 16 valves with increased spring pressure?

2) Will over shimming the springs for better control help me if I have stock heavy valves, locks, and retainers? Do I need this for a motor that will redline at 6600-6800 rpm?

Thanks again.

Fbodyjunkie06

iTrader: (10)

I would say you would gain hp due to better control over the valves if anything not lose.

Jason 98 TA

iTrader: (4)

The 1518 spring is a nice part & if you buy ANY brand single spring from TSP we will give you a new set of spring seat/seal combo FREE!!

xlcooplx

iTrader: (26)

Guess I'll be getting in touch with you when I order my PAC 1518s!

PREDATOR-Z

1- No Hp loss, but your lifters will have to work harder. Why? .650 and 130lbs are plenty for that mild cam.

2- Stock valves ar not heavy, it will be plenty to go at your desired rpm.

3- Side effect of shimming and adding spring pressure is reduced spring life, so why do it unless necessary.

4- A long as you have proper preload on lifters, 1.800 install height is all you need.

5- Note that with aftermarket beehive, always warm the motor and let it reach operating temp before beating on it. Those springs can be brittle when cold.

6- After install, you'll have to go through 2 to 3 "heat cycles" before beating on the valvetrain. Heat cycling is getting the motor hot and then letting it completely cool down then repeat. I prefer 3 times after short drives and no more than 4K rpm when hot.

Mark

KennethS

Not sure what you mean by the springs being brittle when cold. They are coiled cold and do not break then... I would say the springs are already "broken in" or more correctly relaxed when they leave the shelf, but the degree depends on the batch.

PREDATOR-Z

The alloy they are made from is brittle when cold and needs reaching operating temperature to gain elasticity if you wish. (but is more an issue of harmonic vibrations than tentional stretch)
All new springs have to go through atleast 2>3 heat cycles before being beaten on.