Hello all, I have a slight dilemma on my hands...I took my roller block and vortec heads to the machine shop for some work. To make a long story short I have them modify my heads for use with my cam (xr276hr) and a set of lt4 valve springs. I gave them the installed height, and cam lift specs to work with. I get a call from them telling my the lt4 springs will not work they coil bind, they have a set of springs they run in the circle track cars alot which will work for 38.00. So trusting they knew the low down on my heads and engine I said go ahead. Well come to find out the springs cannot be used with a roller cam...the heads are bolted on. So what is the difference between roller cam springs and non-roller cam srpings, and should the lt4 springs work with the cam I have? Sorry for the long post, but all comments are apprieciated!

 

Why do you think they can't be used with a roller cam?

 

Because I got a little funny feeling and called them up today and they said they couldn't be used with a roller cam, is there really a difference? They are all out right now so I can't call back to get the low down.

 

Ok...so the machine shop closed early today...at least I got the manufacturer of the springs when I called earlier here are the specs:

1.780" @ 125# Installed height
1.160" Coil Bind
325# Open Pressure
.550" Max lift

Crane Cam recommends the following:

3) HYDRAULIC ROLLER CAMS require higher spring seat pressures to control the heavier roller tappets and the more
aggressive opening and closing rates available to roller cam profiles.
a. Small Block applications: 120-145# seat pressure
b. Big Block applications: 130-165# seat pressure

4) HYDRAULIC ROLLER CAMS use higher open pressures to control the high vertical opening inertia of the heavier roller
followers.
a. Small Block applications need at least 260# for general driving applications up to 4000 RPM.
b. Moderate performance small block applications like 300-360# open.
c. Serious small block applications can tolerate 400-425#* open pressures and still expect "reasonable"
valve train life when top quality springs, pushrods, and lubricants are used.






So based on this information do you think the springs I have will work or should I get back in contact with the machien shop on tuesday? Thanks!

 

Anybody have any suggestions?

 

1.780" @ 125# Installed height
1.160" Coil Bind
325# Open Pressure
.550" Max lift

If this is the real specs of your springs ( you need to remove one and check)
And your cam is the .502-.510" lift cam ( comp XR276H10) using 1.5:1 rockers I would shim the springs for a 1.73" installed height. Should give 130LBS seat pressure with the required .060" coil bind clearance at full lift. Do not use with 1.6 rockers.
Should be good to 5800-6000rpm More than enough rpm.
if you just got to have more rpm get a "Hydra Rev kit" from AFR.
Some things you just have to do for yourself.

 

I'm running the same cam, and these are the springs I chose: Brand: Isky Racing Cams
Product Line: Isky Valve Springs
Part Type: Valve Springs
Number of Springs Per Valve: Single
Outside Diameter of Outer Spring (in): 1.260 in.
Coil Bind Height (in): 1.150 in.
Damper Spring Included: Yes
Spring Rate (lbs/in): 350 lbs./in.
Inside Diameter of Outer Spring (in): 0.886 in.
Valve Spring Style: Standard
Coated: No
Quantity: Sold as a set of 16.

Valve Springs, Single, 1.260 in. Outside Diameter, 350 lbs./in. Rate, 1.150 in. Coil Bind Height, Set of 16

Recommended Camshaft Style Roller hydraulic
Installed Height (in) 1.750 in.
Seat Pressure at Installed Height (lbs) 130 lbs.
Open Height (in) 1.200 in.
Open Pressure (lbs) 320 lbs.
The part# is 235D. For retainers, you can use Isky part# 707-ST or 707-STA. The STA retainers are +.050. My machinist used the ST's and said I'm good to .550 lift. With the STA's, you'd probably be good to .600 lift. Btw, I initially had him install the orange ZZ4 springs, and he really cringed at the idea of using them. Most knowledgeable people will tell you that any of the GM springs are crap compared to aftermarket. In fact, the ZZ4 springs were supposed to have 110 lbs. seat pressure, and my machinist said they were only at 90 lbs. when he measured them. I just remembered you're running the vortec heads. I'm using 083 casting L98 heads. The vortec heads have taller guide bosses, so you'll probably have to get them machined down some and use positive type valve seals on both the intake and exhaust guides to achieve the same amount of lift clearances as I did.

 

Good deal, thanks for the info guys, I'm gonna pull one of the springs and check for myself and go from there.

So what I have concluded from this is there is nothing that says a spring can be used for a roller cam or not, it's just based on the seat/open pressure that the spring provides, am I correct in this way of thinking?

Thanks again!

 

For your purposes, this time, yes. Your set up is not that radical. The amount of rpm you'll need for max performance is not that high.
The valve action (rate of lift) is not that high.

A different situation ( more radical lobe, higher rocker ratio, rpm,) would, could will require a more specialized spring.
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For your purposes, this time, yes. Your set up is not that radical. The amount of rpm you'll need for max performance is not that high.
The valve action (rate of lift) is not that high.

A different situation ( more radical lobe, higher rocker ratio, rpm,) would, could will require a more specialized spring. There is a lot more to valve springs than just that.