valve spring pressure help

[toolguy874.1]

would like some input on what spring pressure to run with new cam
it is a billet Hydraulic roller from Weber
current set up with springs 100# seat pressure ,300# open pressure
i spoke with Comp they said anywhere from 110#- 165# on the seat and 285-385 # open pressure
my thoughts are 130# seat 330# open

any info would be helpful

 

[toolguy874.1]

Here is copy of new cam card.
206/206 in signature has been removed.

 

[turbo nasty]

Comp cams 941

 

[toolguy874.1]

thanks for part#
would you install both intake and exhaust at same seat pressure ?

 

[forcefed3.8's]

PAC 1201.

 

[toolguy874.1]

thanks Rob
what do you suggest for install pressure
exhaust install height is 1.770
intake is 1.740
with no shims

 

[earlbrown]

Do you have oversized intake valves that are protruding into the combustion chamber? With the valve tips .030" lower and an at least a 1.55:1 rocker, you might end up needing longer pushrods. There's a chance you're not going to have any lifter preload.


Also, ALWAYS choose PAC springs over mexican Comp springs.

 

[toolguy874.1]

Yes bigger valve and intake is sticking. 030 past exhaust.
I have Harland sharp roller rockers. 1.55or 1.5 can't remember.
I have adjustable push rod to check push rod length
But I need to get heads together and on block before I can worry about that.

What kinda of pressure would you suggest for setting heads up with.
Pac 1201 say 140# at 1.750

 

[earlbrown]

I'm amazed Comp was so sloppy with their poundages. That's a very wide range ESP considering how slow out engines turn.


I've got a cam close to yours, it's a 215/220 with a little over 1/2" lift and O/S valves. I set my beehives up at 125 seated and I THINK I was right at 350 over the nose. That was after vibro polishing the springs and leaving them squished in a vice overnight before setting up my heads.

I never bothered to go back and check them after they took a set.

I stuck my intakes into the combustion chamber as much as I could and still get a good valve job but my tip height didn't drop down near as much as yours.

 

[toolguy874.1]

Thanks for input.
Explain this "vibro polishing"
Is this like vibratory tumbler with ceramic media?
Is this used to take stress out of Springs when manufactured and heat treated?

 

[dank GN]

I personally would run alil higher on the seat like 145-150 closed and around 375-385 open . After the first heat cycle you lose about 10lbs .

 

[turbo nasty]

thanks for part#
would you install both intake and exhaust at same seat pressure ?

I take all springs and get them checked and write the lb on the springs then inevitably you will have some springs that are a lil taller installed as the shims are certain thicknesses and Ill slap in a lil hotter spring in a taller pocket.
I check ever single valve pocket for install height.
Then based off the shortest one I set them up. Of course youll need to know your cam lift and all that with what rocker ratio, etc for proper calculation. I prefer to get them tighter vs looser as they are going to diminish with heat cycles and time so the tighter setup and youll have a stouter spring for longer. Run the new springs until engine is full ops temp and then let them cool to amb temp.

 

[David Husek]

would like some input on what spring pressure to run with new cam
it is a billet Hydraulic roller from Weber
current set up with springs 100# seat pressure ,300# open pressure
i spoke with Comp they said anywhere from 110#- 165# on the seat and 285-385 # open pressure
my thoughts are 130# seat 330# open

any info would be helpful

Valve springs need to be set up correct or they fail. Choice of valve springs depends on many variables such as rocker ratio, camshaft material, camshaft lobe, timing set, max engine RPM, retainers, locks, roller lifter choice. ect. Valve springs need to be installed .060"-.080" from coil bind depending on valve springs choice and manufacturers recommendations. No exceptions here. The lobes on that cam are not too aggressive but have some good lobe lift. I would find a valve spring with 150-160# on the seat and at least 380-400# open. Installing 941 springs with light weight retainers at 1.680"-1.690" would be a good option. Any questions feel free to give me a call.

 

[toolguy874.1]

I purchased pac 1201springs from Weber.
Summit and pac were out of stock unless buying 16 springs.
Weber is only 15 minutes from my shop.

I have pac valve micrometer and proform digital pressure gauge.
Springs in heads with 206/206 were 100 on the seat.
I also had some new Springs from 20 years ago when I first built this engine.
They measure 165 on seat 420 open.
Seemed at bit much.
Tomorrow I will be measuring new pac Springs.
I got confused when I called Comp Cams and they gave me such wide pressure requirements.
I didn't know how aggressive lobe where so I wanted to get more professional opinion of the pressure required.
Thanks Dave
And for all responses

 

[toolguy874.1]

I have measured all the spring pockets with with install height micrometer
Exhaust are all within .004
Intake are within .002

 

[toolguy874.1]

Valve micrometers are in increments of .0025 so I guessing that is within spec?
I measured each head twice
Each time coming within. 001-.002
Of previous measurement.

 

[BEATAV8]

I have a cam with those same lobes, just flip flopped int/exh. I set it up with 150lb @ 1.1680 and 395lb @ 1.163, 0.103" from coil bind.

The springs I used had been sitting on the shelf for a while, I think they were K750's which I removed from some GN1 Aluminum heads.

 

[forcefed3.8's]

I purchased pac 1201springs from Weber.
Summit and pac were out of stock unless buying 16 springs.
Weber is only 15 minutes from my shop.

I have pac valve micrometer and proform digital pressure gauge.
Springs in heads with 206/206 were 100 on the seat.
I also had some new Springs from 20 years ago when I first built this engine.
They measure 165 on seat 420 open.
Seemed at bit much.
Tomorrow I will be measuring new pac Springs.
I got confused when I called Comp Cams and they gave me such wide pressure requirements.
I didn't know how aggressive lobe where so I wanted to get more professional opinion of the pressure required.
Thanks Dave
And for all responses

I didnt realize you are close to Weber, where at?
I set the springs up like Dave said, .060 to .080 from bind. 400 over the nose.

 

[toolguy874.1]

My shop is in Grafton.
I talked with you at Drag week at Norwalk this year. Helped work on Gn in the pits.
Spent Sunday working on heads.
Just ordered -.050 locks and new retainers from Dave,
To put pressure closer to what I wanted.
Should be here tomorrow. So I should be able to get heads together this weekend.
Thanks for you advise!
Hope to see you around track this summer.

 

[forcefed3.8's]

I remember now.
One of the most overlooked items on these cars is the valve springs. They need pressure.