Can someone educate me on the terms checking height, open height, binding height, installed height, etc. in regards to valve springs. I'm particularly interested about understanding binding height and am getting confused while looking at catalog specs. Seems the higher the bind height, the greater the spring pressure (in most cases). That goes against my logic.

 

Go to Comp Cams web site. All the information you want is on their web.

 

Thanks for the steer.

 

Ok, I went to their website and did some reading. Two thing that I still don't understand. Is binding height = max height that the spring can compress safely? Is installed height - binding height = max valve lift?

 

This is Crane cams over view - not what you really wanted.
http://www.cranecams.com/camvtfaq.htm

If your worried about your springs and I would guess that is what started all this. Find out the lot number or numbers of springs that have a % of failures. then find out how they were set up and what cam profile was beating them up.

quote: Can someone educate me on the terms checking height, open height, binding height, installed height, etc. in regards to valve springs. I'm particularly interested about understanding binding height and am getting confused while looking at catalog specs. Seems the higher the bind height, the greater the spring pressure (in most cases). That goes against my logic.


I'll look up a real good article for you in CHP

Your installed hieght is Generally a spring manufacturer will tell you set it to1.8 inches and you will have 100 pounds seat pressure. So your head shop or you either adds copper shims or grinds out the spring seat so every spring has the same height and hence spring pressure. Then real good shops take the time to grind each valve tip so they are all the same height.

Lets say. your installed height is 1.8 inches and your rocker total lift is .500 inches. Well that will smash the spring down to 1.300. What you have to look for is the type of guide and seals your using to make sure that the retainer doesn't crush them. Cam companies also give a coil bind number. Well they rate this spring for max of .560 lift and an installed height of 1.8 inches Lets say you bought thicker retainers or over shemmed th spring. So it's actually at 1.7 1.8- .560 = 1.24 coil bind. now you still have a .500 lift cam and you think your safe 1.7-.500=1.2 and your crushing the spring together.

oil cools the springs so never run heavy rotators and lash caps. the springs at max lift should never touch some of the coils together.





[Modified by gkull, 5:40 PM 10/31/2001]

 

So, max spring compression = binding height + .060

"you think your safe 1.7-.500=1.2 and your crushing the spring together" :confused: :confused: :confused:

 

What I’m saying is my hypothetical springs are rated for .560 lift at an installed height of 1.800 inches. Which would mean that the factory claims that "coil bind" occurs at 1.240 "compressed height.

So Bubba the mechanic knows his cam is only .500 lift. So he thinks he is safe slapping the heads together. But he never thought about his special racing chromemoly retainers cause a 1.700 inch installed height with his brand of keepers. Well he fires it up and has broken damper inner spring metal everywhere.

Every reputable manufacturer has a fudge margin in stating the max valve lift rating of a spring because he wants you to be happy and his product to last a long time.

I came to the conclusion long ago that your better off over springing. What I mean is "valve float" is very destructive. It still happens to me one of the last motors I tore down had signs of piston valve impacts in 2-3 cylinders. I never even remember when it might have over revved that bad. So what I do is. I install bigger diameter higher pound springs. Common hydro flat tapped cams might use less than 100 pounds of closed seat pressure. But I have for example a CC274 XE cam and they recommend a 1.26 dia spring with 110 # closed with an installed height of 1.810. So what I did is installed 1.46 diameter springs with a 155# pressure closed rating at 1.810. Well every mechanic knows that 155# springs would beat the lifters to death and cause flat lobes. Stamped rocker arms might last a day and you would have to have very good push rods. So what I do is. Retainers and keepers can be purchased in a variety of heights. I would play around with combos and end up with say 1.900 installed height. So the spring has less compression and now gives me 120# closed pressure. Comp cams card said valve float at 6500 rpm with their 110# spring. Well I just installed monster springs and valve float might be 7400 rpm. Not just because of 120# closed pressure , but the open pressure might be 100+ more pounds than the recommended 1.26 dia 110# springs.





[Modified by gkull, 9:52 AM 11/1/2001]