How to select valve springs?

[TheNeedForZ]

Suppose one is to say "I need to put together an engine that needs to rev to ---- RPM and I want to minimize or eliminate valve float and valve bounce. How does one choose the valve train components?

 

If valve lift and cam lobe profile are not compromised, what are the things that can be done to minimize valve float/bounce? Is there a math formula for choosing a spring that will minimize valve float/bounce at given RPM knowing mass/inertia of some components?

 

Thanks

[Brad-ManQ45]

The easy answer here is to get the cam you need for the power range that you want, then get the springs from your cam manufacturer.

 

They have a vested interest in providing compatible components.

[dr_hunt]

Good advice actually. Valve train dynamics is extremely difficult to model. Cam manufacturers have spent countless hours using special equipment and high speed cameras to "see" what actually is happening and to evaluate failures.

 

Being that as it is, the big cam manufacturers have the know about what springs it takes to make a particular cam work. Excessive valve spring pressure only creates more wear and heat and wastes power. Getting the lightest valve train is what you really need to concentrate on if high rev's are desired. But even if high rev's are not desired it's still a big bonus in my opinion

[grumpyvette]

you might want to look into BEE HIVE VALVE SPRINGS, if they are available for your application. they allow both a lighter spring with the same pressures and a smaller dia, and lighter weight retainer , giving greater rocker clearance and lighter inertial loads at high rpm

check with your cam supplier they tend to cost slightly more but they can give you some additional rpm capacity and lower stress

keep in mind the seat dia. on the heads is usually limited or set by what can be machined ,the coil bind or stack height and installed height must match the cam lift clearance and and both the open and stationary s, issues like inside dia. and distances between retainer and valve guides ETC. dictate the valve seals that can be used, spring loads must match the application, yes

when you sellect a cam, the cam supplioer will generally suggest matched springs, and an installed height and matched components, and yes they have a marked interest in your engine performing well , so they will tend to give good info, they are NOT just trying in most cases ,to increase thier profits by selling you stuff you don,t need.

yes stock springs are fine IN SOME APPLICATIONS, but you must ALWAYS check spring clearances and loads and valve train geometry

theres a big differance in spring quality between the O.E.M and the better aftermarket springs and running double or triple springs can at times be an option, remember lighter valve train components usually reduce stress, allow less spring pressure and resulting valve train wear, and tend to increase the rpm range

 

http://www.racingsprings.com/beehivesprings.htm

 

 

http://www.ovaltracking.com/tech/2006/i_1-beehive-3.html

 

 

http://www.dougherbert.com/1445beehivesprings-p-22853.html

 

http://www.jegs.com/webapp/wcs/stores/servlet/product_10001_10002_753897_-1_10699

 

http://www.carcraft.com/techarticles/vortec_valve_spring_upgrade/

 

 

 

Id use any decent quality springs from any NAME BRAND manufacturer reguardless of brand if the specs matched the required clearances and loads, naturally the manufacturer of the cam has a vested interest in your engine running correctly so thier advice should be taken seriously, but because its a very competative market they will rarely point out the BEST springs, opting for the slightly more that adequate choice to keep the costs lower and make the sale, knowing that in most cases thats going to be the best compromise , but I certainly would avoid "deals" from sources like EBAY where your not sure what your getting and they have little to loose selling cheap imported junk, after all its YOUR engine thats going to be damaged if they fail, and quality COSTS more than JUNK!

[TheNeedForZ]

Thanks for the answers. I haven't thought about asking the cam makers. Makes plenty of sense....they have the know-how and want the consumer to use valve train components to match the cam profile/lift(however radical that might be), so the cam can reach its potential, which results in good reputation for their companies.

[Michael]

I was in a similar predicament recently - needed to revise my choice of valve springs, to match my "low lash" mechanical roller cam.

 

Unfortunately Comp does not make a beehive spring for this application - and in fact their tech line counsels that a single-spring (no damper) is risky for mechanical rollers.

 

On the other hand, low-lash roller take surprisingly low pressure (160 seat, 450 open) relative to what's common for usual mechanical rollers, which really confuses tech line guys at the major manufacturers (the manufacturer of my cam, Cam Motion, does not sell springs).

 

I'm probably going to end up with Comp 26094 springs - which are advertised as being for flat-tappet cams. Thought coil bind should not be an issue per se, my machinist recommends extending the 0.060" rule to 0.100" for endurance applications - a standard that the 26094's fail. Crane makes a similar spring good for 0.700" lift, which might be a better fit.

 

Anyway, I'm mumbling here. Bottom line is that some half dozen considerations of spring pressure and valvetrain geometry have to be taken into account, and for the relatively unusual applications there is no good off-the-shelf solution.

[dr_hunt]

tight lash cams have slower opening and closing rates that will allow you to use lower spring pressure rates to control the valves. I'm just curious as to why your chose that cam versus some of the other cam manufacturers?

[Pyro]

use diesel engine oil with your new and stronger springs, as recommended by compcam.

[pparaska]

I also have a tight lash solid roller cam from Cam Motion. The motion is actually quite intense, as far as 0.020" to 0.050" and 0.200" durations, i.e. mechanical intensity. The lash ramps are gradual though. I've gotten good feedback from people on Cam Motion cams - that they spec a very good grind for you, then go into their shop and grind it on the blank of your choice, even one with a pressed on cast iron gear for distributor gear longevity. I personally don't like squishy valvetrain parts and I don't mind at all lashing the valves a few times a year, if that. And the noise is not really objectionable - in fact I enjoy it .

 

BTW, Cam Motion does sell springs from many manufacturers and they are knowledgeable about what springs to spec for their cams.

 

Comp has been slowly increasing the breadth of their beehive spring selection, but not to the point they have anything for my spec yet. I'm using a fairly stiff setup for street, about like Michael's specs. And yes, I have a spring tester to be able to test them off the head periodically. I'd like to get an on-the-head tester too.

 

But if you buy a cam from one of the manufacturers, realize that many of the big name brands test their cams with a Spintron machine and dyno and really investigate the dynamics. They will have a good idea what springs will work but aren't any stiffer than needed.

[pparaska]

BTW, I disagree with the graphic in the post above- that is from Comp Cams and I think that if you read about pushrod length (even threads here) that the numbers are all screwed up in that diagram. The roller should touch the valve tip at (1) at both base circle (zero lift) and at max lift, and should touch at the farthest extent (3) when at MID lift. (2) is seen 4 times per opening/closing cycle, usually near lift 1/4 lift and 3/4 lift.

 

What they show is for a too-short pushrod, and the sweep across the valve and the side loads on the valve guide will be higher than optimal.

 

Of course, I'm willing to listen to other points of view.

[speeder]

My Buick V6 setup from Comp Cams will use their recommended beehive springs, (p/n26120-12) set at 155/375lb. Setup is Comp mechanical roller lifters, cam =.619 valve lift, .016 lash specified, T&D 1.65 roller rockers. This is for an 8000 rpm turbo motor.

 

I've heard lots of discussion on the merits/disadvantages of beehive valve springs.

 

I totally had to rely on the tech guys at Comp for this selection - (Mostly dealt with Tim Cole @ Comp) and will report on how it works/lasts if the motor EVER gets liberated from the machine shop.

[grumpyvette]

"BTW, I disagree with the graphic in the post above"

 

Id agree with you there, a properly set up geometry will barely move the contact point accross the valve tip and not sweep across the whole tip from side to side keep in mind the loads are higher at full and mid lift so thats when the rocker tip should be centered on the valve centerline and when the valves under max pressure vs when seated when its less important

[Michael]

I ended up with a cam from Cam Motion because Pete told me to do it.

 

Actually, I wanted a mechanical roller cam with moderate duration and relatively aggressive profiles, with quite a bit more duration on exhaust than intake (to partially compensate for a small-diameter exhaust tract and poor e/i ratio for my heads). No such cam was available off-the-shelf from Comp, Crane, Crower or Isky. And if I were to go for a custom grind, I might as well pick a niche manufacturer.

 

Carolyn Boone at Cam Motion says that they (Cam Motion, that is) do not have valvesprings suitable for my application. Instead, she recommended 933 springs from Comp. Meanwhile, my prefered supplier ("Wolfplace", in Northern California - he does not post here, but frequents the Chevelle Tech forum) gave the nod to Comp's 26094 springs, which have the right numbers but are quite pricey.

 

So the quandary persists....