So what's in a valve spring?

[73k5blazer]

I'm picking some parts for my Daily driver SBC rebuild, and have come down to valve springs. The cam I want comes in two different kits,
1 kit has cam, timing chain/sprockets, lifters and another kit has
cam, timing chain/sprockets,lifters, valve springs/locks/retainers/seals''

The second kit is like $70 more that the first, and if I don't get them in that kit, the master engine kit that has new springs and stuff is like $30 more.

So what's really in a valve spring? What would comp cams spring have over the no-name stocker?

 

[pauly383]

Different springrates , just like leaf springs . Just like a heavier truck needs stiffer springs , different cams need different weight springs . Stock valvesprings are only good to a certain amount of lift .

When in doubt , get whats reccomended for your cam .

 

[dyeager535]

Dunno if it's required or not, but when I had my (Vortec) heads at the machine shop, the springs are checked to make sure that the pressure is consistent, and they are shimmed if necessary to get them all to within whatever tolerance is necessary.

Curious to hear what others know about valve springs and checking pressure as installed on them in a "normal" application.

That service is included when they install springs at the shop I took them to. I may not have taken the heads there at all except I thought they would have to be machined. Turns out the shop had some heavier springs that they took the inner coils out of that came in at exactly the right pressure recommended for the cam, and ended up being cheaper than buying the springs somewhere else to boot!

These were new springs BTW.

 

[R72K5]

always have springs checked, old ones are just that- old- tired- weak

im getting a set of 93 caprice heads for the 71 dually's engine and im going for a new cam and lifters and springs and rods and rockers and timign set

then there is still oil pump and some other things, but ya know..





when in doubt or engine is known to have high miles then get new ones, stock or z28 ones for under certain valve lift and aftermarket for certain lift and higher


i dont know the numbers though

i think the line is like .440 something

i forget,,

 

[Mad-Dog]

Maybe this will help...

http://www.compcams.com/Technical/CurrentCatalog/HTML/324-328.asp

If we knew what cam you were installing and what heads you have then maybe we could tell you if ya need new springs.

If the cam you install has more lift than the stock springs can handle then you will experience coil-bind which causes broken rockers, bent push-rods etc etc (not good)

If the open seat pressure is too low then the valves will float at high rpm's

If the open seat pressure is too high you are wasting HP just opening the valves, and the cam lobes will wear out prematurely while bending some more pushrods

follow the cam grinders instructions......unless your present springs are compatible

 

[73k5blazer]

Taking alot of this information and digging around a little more, it seems the stock springs are sufficient for the cam I plan on running. Provided of course mine meet stock specification, which has yet to be determined, but if they don't I'll get new ones.
What about retainers, locks and seals? Never built heads before (exchanged them, buy never built). Do the retainers need installed by the machine shop, or can the average joe do that?
Thanks for all the excellent help!

 

[Mad-Dog]

Retainers are sized to fit a particular diameter of spring whether it be a 1.25" or 1.437" or etc.

Valve seals keep oil from running down the guide and into the chamber,
I prefer Viton seals.....Umbrella seals are the most common on a stock head but the guides must be machined for quality press fit seals.

Locks come in 2 sizes, 7 and 10 degree depending on which retainers are used and hold the assy together.

There is only so much you can do with a spring compressor,

You still need to machine the guides for quality seals and check the installed spring height......

You can buy the tools to do the work but it's more cost effective to have a machine shop do it for ya