I've searched and searched..

I am replacing my valve stem seals and installing some pro magnum roller rockers on my 87 L98 in my GTA. So I thought I might aswell change the stock 100,000 mile valve springs. I am not touching the roller cam and I wanted to know which comp cam valve springs I need to use with the stock cam?

Can anyone help? Do I need to replace the retainers and keepers?

Thanks in advance...

 

981

Yes you need the retainers and keepers; and shims and seals as well.

Throw away the oil splash shield that's under the stock retainers, and the stock exhaust valve rotators. Replace them with an equivalent thickness of shims. Use "positive" valve guide seals such as the FelPro ones. 72877 I think is the # you want. Use Comp 4753 shim kits; buy 2 kits just in case. The exh rotators are .100" thick; it requires that much extra shims to replace them.

 

Thanks Sofa!

Ok, I already have the felpro valve stem seals, I bought the ones you said for the intake (positive type), and I have the umbrella type for the exh valves.

This is what is in my summit cart so far...

http://store.summitracing.com/partde...art=CCA-981-16 Springs
http://store.summitracing.com/partde...art=CCA-742-16 Retainers
http://store.summitracing.com/partde...art=CCA-648-16 Collets
http://store.summitracing.com/partde...?part=CCA-4753 Shims
http://store.summitracing.com/partde...rt=CCA-1317-16 Rockers

Am I missing anything? Is one of these parts not right for my 87 L98?

The retainers say they are for 1.250 springs and the springs O.D is said to be 1.254 ???

 

Looks like it should do the trick....

Be aware that those rockers will be troublesome to fit under your valve covers.

 

I was not aware of that!!!! Thanks Sofa!

I live in Australia, so I would be a little upset when I recieved all my parts and found that out!!!

 

Pro magnum roller rockers, stock 1.5 ratio, on a stock cam? Why on earth??

 

Why not. The full roller rockers will be a big improvement over the factory rockers, sure I'm not going to see full benefits when using them with the stock cam, but its definately an improvement over stock regardless of cam.

I'm not changing them over for HP increase, I'm changing them over because I am in the middle of changing the valve stem seals and I am changing the springs aswell. And they reduce friction, are much more rigid than stock, and will probably have better tolerances than 16 rockers that are 100,000 miles old.

 

For stock low rev, low spring pressure, pro magnums, which are designed for racing with very high spring load, are super excessive. Stock rockers will last hundreds of thousands of miles for that app. If you were getting 1.6 roller rockers to help out the really weak stock cam, that might be a slightly good idea, but oh well.

 

The stock cam isnt going to be in the motor forever.. I may change it out in a year or so.. The pro magnum roller rockers arent going to do any damage in the meantime with the stock cam are they?

 

Nope, won't hurt a thing. You'd probably gain more HP by having a valve job done on 100k mile heads than switching to those rockers though, $ for $

 

Those rockers are very nice. They're expensive but if you want em on there, keep 'em. I've got em on my Vortec headed 350 and I KNOW it's overkill. I'm gonna be pushing barely 300 at the wheels I bet. I also had to deal with clearancing the valve covers... not fun or easy. Probably easier with stock style covers.

Also, those 981 valve springs are supposed to work fairly well with the stock cams. I actually just sold a set of those valve springs, retainers, locks, and o-rings from my cam kit (Decided I didnt need them) for $90 shipped. But I'd bet you could find another set for around that price, but mine were brand new in the box also. The springs are $60 and so are the retainers you'll probably want for them. So that's $120 new. Not all that much.

 

Thanks Infernal, would buying tall valve covers fix the clearance problem with the pro magnum rockers? Such as these http://store.summitracing.com/partde...5&autoview=sku
Or is it the internal bracing inside the covers that dont clear the rockers?

 

It's the internal bracing where the bolts go through. You can clearance them, it's just work.

 

i'm running the basic comp Magnums in the 1.6 ratio on my L98 with no clearance problems. i'd stick to those rockers in the 1.6 ratio as they are cheaper, fit fine, and will give you extra lift which will indeed make a few more ponies....

but if you have the money to blow then go for it

 

What valve covers do you have? Im curious.

 

if thats directed to me, i have stock L98 valve covers