Basically the machine shop told me that I didn't need shims on all of my springs. Is this ok with my Comp 26918 springs? I was under the impression with our LT-1 aluminum heads we needed shims on all of them. The machine shop told me he couldn't get the right hight, so he didn't need shims on all of them. As for shims, I mean the washer thing under the valve spring. I apologise for not being knowledgeable on this.

Thanks for the help before I bolt the heads on:

ZMAN

 

You must have seats on aluminum heads. The only application where no
seats are necessary is on the iron head LT1 impys.

 

He might be implying that he doesn't need any shims under the stock shim/locator....because there HAS to be something for the spring to sit on with aluminum heads.

Secondly - doesn't need them on all of them??? if those installed heights are soo messed up that he is dropping shims to compensate, he is messing up your heads.

 

Under some of the springs, there are these thin washer looking silver plates, a little bigger in diamater then the spring itself. Some of the springs have them, some of them don't. I could take a picture or 2 and email them to anyone to help verify.

Are valve seats the physical part of the head that is flat that the valve springs sit down on? Or is the seat a part that one buys to put under the spring? I guess I'll have to do some searching for some diagrams.

Thanks:

ZMAN

 

A valve seat is a metal ring that is in the combustion chamber - it has the angles or radius cut into it for the valve face to seat against. Made out of many different materials based on valve type(Titanium, cast, stellite, etc) and fuel type(diesel, alky) Required in aluminum heads, while iron heads generally have parent material seats for the intake and induction or flame hardend seats on the exhaust. The spring seat is not always a seperate piece of metal, it just generally refers to the area that the spring sits. Then there are flat shims for adjusting installed height, and locators, which have a positive hold on the springs.

What you are refering to are shims under the stock locators to compensate for unevenly cut valve seats. I don't consider it to be a problem if ALL the exhaust, or ALL the intake have a common number of shims, it's okay to stagger the intake/exhaust valves in order to compensate for valve margin thickness and chamber shape, but not to have same type valves .010" out from each other.

 

He is probably referring to the seat/shim/locator that is located between
each valve spring and the head. If this is the case then you need one
for each spring so that the steel spring is not in contact with the
aluminum head. He may also have shims in addition to the seat/shim/locator
to achieve the desired installed height.

The bottom line is that you need something to keep the steel spring from
contacting the aluminum head under each spring, regardless of what you
want to call it. Besides protecting the aluminum head, the seat/shim/locator
will "locate" the spring and keep it from walking around. This was a big
beef with the Crane 10308-1 kit because springs would walk on the shims
and chew up valve stem oil seals.

 

Thanks guys:

I defenitaley understand heads and valve springs more than before. They are a lot more complicated then they seem.

My springs didn't have the locators on them. The machine shop ordered them today. I might have my heads back by friday if Im lucky. I sure aint going to pay for any more labor on those heads. The machine shop told me they have have all the necessary parts. They told me to get the cam and springs and they will handle the rest.

Thanks to you guys I am pretty sure my motor is going to last another 100k miles

ZMAN