Ryan23silverado

iTrader: (1)

What is the purpose of shimming valvesprings? Is it simply to get them all to the same seat pressures or is there much more to it than that?

If I switch valvesprings, do I need to shim the new ones too?
I have changed valesprings before on other head(s) and have not shimmed. Are things okay if you take a shimmed valvespring and put in some new springs with no shimming process done with the new springs?

Thanks for the help
Ryan

Cstraub

iTrader: (1)

Shimming is serves 3 purposes. It allows the engine builder to get proper seat pressure with new springs when assembling heads. It also helps protect aluminum heads from the spring "digging" into the head. On rebuilt heads with old springs it allows the builder to gain pressure without replacing the spring if there is enough clearance between max lift and coil bind.

Cstraub

Ryan23silverado

iTrader: (1)

okay makes sense. Thanks Cstraub.

So I guess you really don't Need to shim if you put in new springs, correct. Would it be okay to keep one shim in there to prevent 'digging' into the aluminum head? Would it would matter too much on the 'digging' issue if they were just the '02 LS6 springs that were to be used? i.e. they don't have near the pressures of some dual spring, so they wouldn't dig...?

Ryan

Cal

iTrader: (1)

You need to have some kind of shim or washer between the spring and an aluminum head for sure. Why not just re-use the the stock shim?

SLowETz

iTrader: (12)

Are you talking about shims, or the locators???

Locators will keep the spring from digging into the seat. Shims allow different installed heights. I guess you could just re-use the locators w/out shims, but installed heights "could" vary as the springs themselves can vary to some degree. Knowing your installed height is important if you care about your bind #'s. It's good practice to at least check the installed heights when swapping out springs. Coil bind is NOT your friend.

Ryan23silverado

iTrader: (1)

They look just like washers underneith the springs. What are locators LowETz?

Coil bind should not be a big concern as I am only lifting .555/.551. I will be using '02 LS6 springs which are rated for that exact lift also.
When you look at stock GM LSx heads there is no spacer below the stock valvesprings...but you think it would be a good idea to leave one of them on from the heads I will be swaping out to '02LS6 springs on?

To clarify here is what I am doing: I have stage2 Pat.Perf. LS6 heads that have Crane dual valvesprings -underneith them are the shims (or are they 'locators') I will not be needing nearly that much spring (chatter sets off knock sensors easily in the '99 trucks), so I will be running '02 LS6 springs.
So just keep a shim underneith the '02 LS6 spring when I install them just for protection anyway?
Thanks again,
Ryan

Pro Stock John

iTrader: (34)

Shims- Allow you to get uniform installed heighths, and to get the right installed heighths for your camshaft.

Locators - Keep the springs from moving around in the spring pockets.

J-Rod

Exactly.

Now, here is some more useless information on why springs shims are important. As stated. They help get your setup height right. Well, why is setup height important? That setup height is important that you are compressing the spring enough for it to do its job, and not so much that you end up wuth CB (coil bind). Coil bind will kill a camshaft by flattening the lobes. It can also break rocker arms, etc... from the mechanical forces at work (something has to give).


One of the issues I see on here is many folks throw on a set of springs for a H/C pacakge and never bother to check things like setup height or anything else. This is one of the key reasons for folks breaking springs. Uncontrolled harmonics and valve float from insufficent spring pressure.

Remember this, the further the open lift spring is from coilbind, the lighter the force over the nose, the more chance to slam the coils together. For instance you'd set circle track springs at .035 from CB, prostock at .050 from CB. The only reason the PS springs need so much room is that these heavy triples get very tight just before CB and put extreme loads on prods.
If you get numbers on your springs you can estimate what difference shimming would make. Take the mfrs numbers of installed ht, seat pressure, rate, and distance from CB. If a given spring is 120# @ .085 from CB and you want to squish it to .035, you are adding .050 shim. This .050 times a rate of 344# per inch is 12#. Add this to the 120# seat and you see 132# on the seat. Same thing for adding lift while maintaining distance from CB. Add .050 to your installed ht DECREASES seat pressure by 12#. Anyway, all this means nothing unless you know what shims are and where to put them.

2xLS1

iTrader: (25)

For your application, just get some 02 and up LS1/LS6 valve guide seals. They incorporate a .045 spring seat with the seal all in one piece which is .010 thicker than a stock 97-01 LS1 spring seat.

INTAKE V/G SEALS – 12482063
EXHAUST V/G SEALS – 12482062

Ryan23silverado

iTrader: (1)

No, that is some good information J-Rod thanks for explaining how things work man. I will have to read it several more times though lol.

2xLS1 - thanks for the good advice. Thanks even more for posting the pt#s in your post too I will do what you recommended. So I just slip on the valve seals which already incorporate a spring seat and install the LS6 spring...sounds easy enough.

Thanks again guys!

Ryan23silverado

iTrader: (1)

gees, I just looked up those pt#s for the seals on gmpartsdirec.com
GM PART # 12482062
CATEGORY: Engine Valve Seal
PACK QTY: 1 CORE CHARGE: $0.00
GM LIST: $20.11
OUR PRICE: $11.46
DESCRIPTION: SEAL KIT

Is that for one seal or eight?
$172 for seals -I hope not...

2xLS1

iTrader: (25)

The seals are only sold in packages of eight. That price is for a package. That is the only seal I use now on single spring setups regardless of the year. Just be sure you remove any spring seats/shims that are already on the heads now. You don't want to stack the new seals/seats on top of anything unless you are using a spring installed height mic and are shooting for a specific height. I'm sure the new seal/seat combo will get you close enough for your application as you described it. Obviously you will need to remove any seal that is on the head now to remove the spring seats presently on the heads.

Ryan23silverado

iTrader: (1)

I understand. Thanks again 2xLS1!

Cal

iTrader: (1)

Actually, the terminology is used somewhat interchangeably by the industry. If you go down to your local GM parts counter and ask for spring locators, they will just go "huh?" In their system, the locators are listed as "valve spring shims." Yet many aftermarket suppliers will refer to them as spring locators.