Valve Spring Help

[TomO]

I have one of the Comp Cams XE262 cams in a 355 SBC that I have in my 63'. I have been very happy with the performace and characteristics of the cam. There is one thing that has been nagging at me for some time. Comp specs the 981 valve spring that has 110 lbs on the seat / 285 lbs open and a spring rate per inch at 400+lbs. The tech at comp was very specific in telling me that the springs I needed to use are the 981's. The machine shop intalled as set of Speed Pro VS7397 (commonly refered to as Z28 springs) which are rated at 104/277. I would like to swap the springs out so that I have the correct part in place but have some questions.

My questions are:

1. Will the comp springs be fine to run with pressed in rocker studs? I plan on leaving the heads installed on the engine and swaping out the springs. The heads are stock 882 castings.

2. Will switching springs over cause any problems with the mechanical aspect of the engine. The engine is now 5 years old and checks to still be very sound. I do notice however that when I run the engine rpm up to 5300 the valves do start to FLOAT.

3. Will I notice any performace gain at the strip....ok this is the real motivation to change the springs out. The class index that I race in has just been lowered to 14.20 and my car currently runs 14.40 - 14.35 and I would like to be a little closer to the top of the class.


Thanks,

TomO

[fatride]

Tom, I would not run a performance cam with spring pressures approching 300 lbs. unless the heads had screw in type rocker studs. Nothing like pulling out a stud at 6000 rpm, WOW! I have included the spring chart from Comp. check the ID/OD of the springs and make sure they will not interfere with your stock valve boss and seal! I would say if the Comp sring has the same dimensions as the Z 28 spring you will be alright. Just to be on the safe side of things I would treat the spring change as if I were installing a new cam and break them in accordingly. Your cam should be work hardened and take too the new springs without any problems. I has been said that installing the correct springs will gain in performance through all the rpm range!

http://compcams.com/Technical/CurrentCatalog/HTML/340-349.asp

[Firepower354]

Tom, There's nothing magic about the 981's. They are a good drop-in spring for the price though, and should keep you out of float. The Z28's may have sacked-out with the aggressive ramps of your cam. If you have or plan to swap to 1.6:1 rockers you'll need different springs though. You'll want stiffer pushrods, if you don't have them already, at higher rpm's. You can use a screw-in stud with a small shoulder instead of a hex head, such as Mr. Gasket's from Jeg's #720-1076 at @27.99 and tap the heads on the car using a guide like Jegs #778-66783 for $16.99. You'll have to drain some coolant and stuff a few rags to keep the chips out of the pan. Grease works too, just shopvac and pick the remaining chips out with a magnet. If you're floating at 5300, you'll see an improvement with better springs. Without knowing the rest of the combo, that's all I have. Mid 14's is good for a set of 882's. Something a little better breathing might be in order, if you've super-tuned (timing curve, jetting, etc) all you can get from it. I have Vortec's and iron & aluminum Sportsman's all on my bench being readied for sale....

[TomO]

Fat and FirePower - Thank you for the replys. I have heard and read horror stories about pulling the studs from the heads. Could I pin the studs instead?

Sounds like I will pick up alittle performace by making this swap. I have no plans on spining the engine past 5,500. I know that I am getting just about all there is to have out of this engine. I am just going back thru things and tweaking here and there so that I do not have to run the gutts of of it to be competitive/consistent. I believe that I am "there" on my tune up. This engine need to live until my 409 come to life in a couple of years.

TomO

[dq409]

Firepower, I would be interested in those heads you are ready to sell.
Email me with the info on them please

I have this weird plan to run a big blower on my Rambler and need a set,,,dq

[biscaynewagon]

I have this weird plan to run a big blower on my Rambler

Cool Jimm, right on.... but hopefully you don't have any plan to put a bigger mailbox in that Rambler :D
Sorry man, can't help my self :rofl

[Firepower354]

Tom,
You can pin the studs, but I think with the tool listed you'd be as well off to pull and replace them. It's not a bad task.

DQ,
You sick man. I like you already. I'll email the details.

[SS425HP]

But, firepower, you have never met him in person. It gets worse :rofl He's just nuts on the forum, in person, he's WHACKO. :beerbang Many at the convention can attest to that. :clap

[dq409]

Cool Jimm, right on.... but hopefully you don't have any plan to put a bigger mailbox in that Rambler :D
Sorry man, can't help my self :rofl


Sorry ,,, no mail box on the Blurrrr !! Just that BIG jimmy sticking out of the hood !!!

WACKOWACKOWACkO :stooges :brow

[TomO]

Guys thanks the help - I ordered my parts today!!!

TomO

[64ss409]

Sorry ,,, no mail box on the Blurrrr !! Just that BIG jimmy sticking out of the hood !!!

WACKOWACKOWACkO :stooges :brow
Does that mean this would not work :dunno :rofl
Ron

[dq409]

Voted best mail box !!!! You win !!! :cry

[TomO]

Guys I got my part together to change out the valve springs. I took the valve covers off and now I have another question. Under the stock retainer there is a cup that goes over the top of the spring. Do I need to use the cup? If I do not my installed height of the spring is perfect. If I do need to use the cup can I take the .030" shim out of the spring pocket and run the spring against the cast iron on the head?

TomO

[Firepower354]

That's just the oil deflectors. If the seals are real good you don't need em. They won't hurt anything if you use them. The springs will run fine on the cast iron head.

[TomO]

FirePower - Thanks a bunch for the info!!!! Now I need to run down a set of the rubber orings that go just below the keepers and I will be all set.

TomO

[fatride]

Lose the cups, just adds reciprocating weight. ;)

[JokersBel]

I know this is after the fact...it seems you're not going to use studs, which is a good place to save some money for you, i mean that as the 882 heads are prone to cracking failure, especially with ANY kind of performance application.

I understand your situation with what that engine is used for and that's cool...i had decided to use 882s on a 350 so it'd be unleaded. It took 5 heads to find 2 without cracks, and of course they have small valves. If some day, you decide to use this engine for more, swap the heads for something better.

Jim