Valve Spring Pressure
 

I was wondering if someone could comment on my spring pressure and tell me if I am in the ballpark. It's 330/250 E-Heads 2.19/1.77 an Ultradyne solid roller with .3994 lobe lift on both intake and exhaust. Duration is 264/270 @.05 on a 108 LSA. It's requiring a lot of shims but I have spring seats so I think that's OK. The IH seems to vary a lot from valve to valve. I am shimming the IH to around 1.760 +/- and am getting around 240 on the seat and between 598 and 612 open at .659 lift using 1.65 rockers. If using 1.5 rockers the lift is .599 and open pressure is 560-570 and I think that's a little low and don't want to put any more pressure on the seat so will plan to use 1.65 to get more open pressure. Thoughts please.

I run 230# seat pressure (when installed, not sure what it is now) and 700# open pressure with the cam in my sig. It has around 0.640" lift with 1.65 rockers and my installed height is about 1.890-1.920". I shift at 6500 rpm and cross the line at 6700 rpm. I use 0.060" spring cups with shims underneath in Eddy heads with 2.19/1.77" valves CNC ported to 335 cfm. I think your spring pressures are fine unless your expected rpm is higher.

If your not getting break up at your shift points / peak rev’s and your lash is holding and your also not seeing any of this taking place as in my photos then I say your good and enjoying the benefit of more HP from less friction.

Do you know what the coil bind is on your springs? 1.76” IH with 1.65s might be getting a bit tight? You may want to try to would shim the seat pressure so it is balanced out with a plus 050” distance from coil bind, take the hot lash off the lift numbers. As long as you get the coil bind distance correct with the pressure numbers mentioned I would ship it.

Unless it is a different .3994 lobe than I am familiar with, the .3994” I recall are not very aggressive roller profiles, you have plenty of spring pressure for it.

I have a little larger roller cam, but 260lbs on the seat and 700lbs open at .750lift. but, from past experience I didn't have valve float or any noticable nosing over at high rpms I checked my springs due to age and they were weak. ( Don't remember what the pressures were) Put on new springs and picked up over 1 mph in the 1/8 mile.

Have you checked to see if a different spring (which has a different rate) could give you the open and seat pressure you with the 1.5:1?

Stan

Hi Stan
Yes, I have thought about getting different springs, but I was already thinking about going to 1.65's anyhow to give me more lift since I believe the additional lift may give me a little more performance based on the head flow. If I can use the springs I have and get the correct spring pressure then I would use them. On the other hand I am not going to cheap out if the pressures on the seat and open are not ideal for my cam.

I @. 6 = 320.4
I @ .7 = 333.9
E @ .6 = 243.8
E @ .7 = 248.4

I would not go with 1.65 rockers just to get needed open pressure .

The added acceleration rate of a 1.65 rocker may need more spring to control it then the added .040” or so of lift can provide, at least in terms of a intake valve that size.

You may be ok on the exh with a 1.65 and the added pressure, and if so then the question becomes will the added duration and lift on the exh side make you more Torque and HP, or less.

A dyno or a drag test is of course a way to tell unless someone with near the darn same motor combo as you has gone Thru the motions to find out and tell you the results .

Sometimes you can bring a motor up to 5500 rpm out of gear and with a thermal gun shoot each header tube and look for a drop in temp which would mean that the motor does not want higher ratio rockers on the exh side.

Were running a 55mm Solid roller .903 Crower lifters. Around 220 seat and 520-540 open. Spinning to 6800-7000 in the 1/4 mile.

So is the above with a 2.19” intake?

Chuckie
Has the valvetrain been lightened up at all? Is this with stainless valves and steel retainers? What is your lift and duration?

I was doing some reading on this subject and found out that I was calculating the valve spring pressure without taking into consideration the stepped retainer. I have dual springs and the retainer contacts the inner spring .100 before the outer spring. So after realizing this I re-calculated the pressures using the retainer instead of just the spring. With the same IH I was using the new Installed height pressure is 262 and open pressure using 1.5 rocker ration is 592 lb. Measured at 1.65 open is 642 lb. The lash is .016 and the lash was not taken into consideration when making these calculations.

I appreciate everyone's comments. I decided not to use these springs, I ordered a set of PAC 1243 springs and will install them at 1.850. I talked to Bullet and they recommended the springs and suggested I use 1.65's with my cam. Bullet is very familiar with Ultradyne cams and the acceleration rate. Funny thing these heads came with the intake valves that are .060 longer than the exhaust. That explains why the had so many shims. I wonder if I will need two different length pushrods to get the geometry correct.

There’s only one way to correctly answer that.

I need to do my geometry, I know

I would measure all the springs for pressure. I have had some-even high end Manley's and Comps all over the place in the same box. Then you wonder does 10lbs variance make any real difference?

Thanks for the tip Skip, If one is 10lbs off do I send it back or just put in another shim

I can't see 10 pounds make any difference. The springs usually loss some pounds after break in. Use it on the exhaust valve as it's lighter. Oh, and my understanding when you measure all the spring pressures, put the one's that have higher pressures on the intake valves as it's a heavier valve. They also want you to do a heat cycle with new springs when first installed from new.

I can't see it making that much difference either as we are all just guessing what each motor really needs for pressure for each cylinder-more theoretical for those that HAVE to have everything identical. Shim it if that does not kill distance to coil bind you need. Also measure every valve's IH as sometimes they are a hair different and you can giggle springs and pressures a little base on that.

It looks like I am going to have the spring seats machined, on the exhaust side only so I can get the PAC 1243 springs installed at 1.850. Because the intake valves are .060 longer than the exhaust valves it is creating a challenge. IH height on the exhaust valves are from 1.826 to 1.840 and the intakes are 1.885 to 1.898. I'll take .030 of the exhaust spring seats and that should do it.