Valve springs

[Paul Secoy]

Hello all, I have a new set of Edelbrock big block heads I need to change the springs on. It's been a while since I fooled with heads much, and only stock ones then. Using a caliper, which I know probably isn't the most accurate, I come up with an installed height of about 1.994", which seems tall to me. I suspect Edelbrock uses some variant of a BB Chevy valve. I have been instructed by Bullit cams to run 160# on the seat, 380# open. I am having a bit of a time finding a spring that fits those specs. I can come close, but either need a different retainer, or have to stack a bunch of shims up, which I really hate to do. Has anyone run into this with the Edelbrock heads?

Thanks.

 

[steve340]

With any head you can get what you are talking about.
As far as I know if you have 7 degree lock there are no plus 50 retainers, you would need to change to 10 degree.
You have not elaborated on what pressure the Edelbrock springs are giving you or how much shim you are talking about needing to use.
Based on supplied info
The best thing to do is source a stronger spring with that installed height.

 

[Paul Secoy]

I'll try to find the notes I took last weekend, but the stock Edelbrock springs missed by a bunch. I swapped a second inner spring into them from a set of MP springs I had on the shelf, and still only could get to maybe 130/350 at .530" lift. The cam company was having a hard time finding a spring due to the increased height. They said there are a lot with a 2.00" installed height, but they were intended for roller applications and were too stiff for my flat tappet. I'd like to find a spring that would work with the supplied retainers, but if I have to buy extra parts, I will. Thanks.

 

[IQ52]

Which Edelbrock head and is it still Edelbrock stock?

 

[Wietse]

I do not think it is a Edelbrock specific issue, this could happen on any head/cam combination, just need to source the right combination.
With an spring pressure of 380# open i believe it is recommended to go with 10* locks.
I've came across some info to only use those with spring pressure of +600# or so.

In your case i would pick using a different retainer over the need to use excessive shims.
Then again, you might require to shim anyhow if there is some deviation between them.

 

[IQ52]

I looked at another of your posts, so they are Edelbrock E-Street heads? The installed height of the springs on those heads is supposed to be 1.88". What lift on the cam?

Help us out here man. The devil is in the details!

 

[Paul Secoy]

My apologies, I have been working 2 jobs and only had a few minutes last weekend for some quick measuring and to test the stock springs, and those I had on hand.

I only had a caliper to try and find installed height, and I likely got it wrong, 1.88" could very well be correct, the steel spring cup on the aluminum heads made it difficult.

The heads are stock E Street heads, and they come with a single spring with a damper. I had a set of MP duals on the shelf, but the spring height was much shorter, and I got squat for seat pressure. I swapped the inner from the MP spring into the Edelbrock springs, but it was still not enough.

The cam is a Bullet solid flat tappet, .530" lift after lash. This is a forced induction build, and they want extra spring pressure to keep from blowing the intake vale open, they want 160# seat, 380# open.

I appreciate the assistance.

 

[Challenger340]

The cam company was having a hard time finding a spring due to the increased height. They said there are a lot with a 2.00" installed height, but they were intended for roller applications and were too stiff for my flat tappet. Thanks.

Whoaa here ? Hold the phone a minute.....

You are trying to find V/Springs for your E-Streets that provide 160# Seat and 380 # Open @ 1.88 or so installed ..... for a FLAT TAPPET Cam ?
Is this a Race deal or do you expect extended street driving/idling etc., duties as well ?

Be very careful with Cam Break-in if you can't somehow lower that 380# open for Cam Run- in ?

Brave lad.... carry on.

 

[Challenger340]

Went back through your posts... so Turbo deal.... I get it now.

Still going to be a chore to run-in that Flat Tappet with 380# open pressure ?
Maybe weld and re drill the adjuster point further out on a set of el cheapo Aluminum Rockers to reduce the RR down around 1.2 instead of 1.5 ?

That's what we did here for Flat Tappet Cam run-in on the Dyno when we can't get the V/Spring pressure down.

 

[IQ52]

My apologies, I have been working 2 jobs and only had a few minutes last weekend for some quick measuring and to test the stock springs, and those I had on hand.

I only had a caliper to try and find installed height, and I likely got it wrong, 1.88" could very well be correct, the steel spring cup on the aluminum heads made it difficult.

The heads are stock E Street heads, and they come with a single spring with a damper. I had a set of MP duals on the shelf, but the spring height was much shorter, and I got squat for seat pressure. I swapped the inner from the MP spring into the Edelbrock springs, but it was still not enough.

The cam is a Bullet solid flat tappet, .530" lift after lash. This is a forced induction build, and they want extra spring pressure to keep from blowing the intake vale open, they want 160# seat, 380# open.

I appreciate the assistance.

If all the information you have given is correct, then according to the Comp Cams catalog, the 939-16 dual spring should work. Interestingly all the stock Edelbrock locators, retainers and locks would work with those springs. I would go to Comp's catalog, look up locators, retainers and locks for that spring and choose the style that fits your budget.

Pull the inner springs to break in the cam without throwing in any boost during the cam break in.

 

[Paul Secoy]

Thank you gentlemen, I've spent a few days on Comps site, maybe I can narrow it down a bit now. I asked about a minimum break in spring when I ordered the cam, and they said 130# seat, 320ish pounds open for break in. I believe the stock Edelbrocks will come very close to this.

They do know it is a street car, and said with the big lifter 400# is about max, and I'm pushing it.

They needed intake valve diameter and boost pressure in Psi to calculate how much extra spring pressure is required, I was impressed by that.

I will do some more research, and let you know which way I jump. Thanks again for the help.

 

[INTMD8]

They needed intake valve diameter and boost pressure in Psi to calculate how much extra spring pressure is required, I was impressed by that.

I don't subscribe to that theory and cannot think of any reason why intake manifold pressure would greatly influence valve control.

As the intake valve is opening you are filling the cylinder through the intake cycle equalizing pressure and compression cycle starts at IVC which immediately and greatly brings cylinder pressure above boost pressure.

Only reason I can see more pressure needed is if you're running a centrifugal SC which may push peak hp rpm/operating range of the engine past the point valve control can be maintained.

In a turbo application however, more seat pressure is needed on the exhaust side as you are needing the valve to close against quite a bit of turbine drive pressure.

 

[Paul Secoy]

Had a few minutes to check things again, I do believe the 1.88" installed height is correct. I rechecked everything and got the following:

Stock Edelbrock singles with damper; 138# seat, 312# open. I'll use these for break in as they are really close to what Bullet suggested as a soft break in spring.

I tried adding the center spring from my MP set again, and it boosted the pressure to; 172# seat, 395# open, too much on both.

The Comp 939's IQ52 suggested are a little soft on the seat pressure BUT, they are listed as a 1.95" installed height, so my shorter installed height and maybe a little shimming should get me there, hopefully the open numbers come in close as well.

 

[INTMD8]

PSI CT1225 is a nice dual spring with only 393lb/in rate.

Puts you at 167lbs @ 1.88 and 375 over the nose if I'm gathering you have .530 lift.

Comp 939 is 469lb/in which would put you at 170lbs @ 1.88 and 418 over the nose with .530 lift.

 

[Paul Secoy]

PSI CT1225 is a nice dual spring with only 393lb/in rate.

Puts you at 167lbs @ 1.88 and 375 over the nose if I'm gathering you have .530 lift.

Comp 939 is 469lb/in which would put you at 170lbs @ 1.88 and 418 over the nose with .530 lift.

Ouch! Does that spring really gain that much going from a 1.95" installed to a 1.88"? 1.95" lists as 138# seat.

Yes, .546" cam, minus .016" lash. .530" at the valve.

 

[INTMD8]

You tell me.

469lb/in is 46.9 lbs for every .100...... 4.69 lbs for every .01

 

[Paul Secoy]

You tell me.

469lb/in is 46.9 lbs for every .100...... 4.69 lbs for every .01

Seemed like a big jump, but my sketchy math says 170.83# Wow.

 

[INTMD8]

Right.

All you have to do is the math based on spring rate.

Starting at your goals of 160 on the seat and 380 open with .530 lift, the spring rate needed to achieve that is 415lb/in. or 41.5 per .100 4.15 per .01

4.15 x 53 = 219.95 + 160 on the seat = 379.95 over the nose

 

[Paul Secoy]

Right.

All you have to do is the math based on spring rate.

Starting at your goals of 160 on the seat and 380 open with .530 lift, the spring rate needed to achieve that is 415lb/in. or 41.5 per .100 4.15 per .01

4.15 x 53 = 219.95 + 160 on the seat = 379.95 over the nose

Thank you for the formula, I was having a hard time with the open numbers, adding the seat numbers would have helped, lol. I will check out the PSI springs, I have never heard of them before.

 

[INTMD8]

I just mentioned it as I remembered it as a lower rate spring.

Anything at 415lb/in rate would get you exactly where you want to be as long as you shim it to the correct installed height. (assuming it doesn't put the spring closer to .060 from coil bind but I don't think you will run into that issue with any spring close to your installed height and .530 lift)

For example, a quick look turns up this spring-

http://iskycams.com/shop/index.php?main_page=product_info&products_id=2137

It's 415 lb/in 150 @ 1.875.

You want 160 lbs on the seat shim it to 1.85 (so .030 shim under this spring on your heads)