if you have a set of heads with springs and no particulare cam,as in heads are for sale,is there a way to figure spring pressure as an average for a certain range of cams.

I would measure the lbs at the installed height you have on em & the lbs at .060 less than coil bind height. . If it is a dual spring compress it with the retainer on top of the spring. Guys said you can use a drill press and a bathroom scale to get a fairly close number. I started to try it but my garage drill press ain't big enough but I one thing I saw was that you need the spring to be pretty much centered on the scale for a legitemate reading.

Thanks that sounds like what i needed to know.

buy one of these testers and use a vice to compress it, works great. You can buy a regular stand to use the same tool as well.

https://www.summitracing.com/parts/cca-5...AiABEgLqovD_BwE

Just run one over to the machine shop, it will take only a few minutes to get the RIGHT information. testing a spring without knowing installed height, coil bind,retainer to guide clearance , closed pressure and open pressure is kind of a crap shoot, You wouldnt be giving the buyer any real useful data.A " pressure" doesnt mean a thing really.

Thank you. These things determine spring load.
Free height
Spring rate
Installed height
Valve open height

There is pretty much nothing you can learn about the spring's specs just by looking at it.

Evarything goes according to the equation F = kX where F is force (lbs), k is the spring rate (lb/inch), and X is distance (inches)the spring is moved from its free state.

Example: Free height is 2.2", installed height is 1.8", spring rate 300lb/in.
Calculation of seat load is (2.2 - 1.8) x 300 = 120lb.

This knowledge is very handy for when you're installing a spring and your installed height is different than the ones in the manufacturers table.

Coil bind height is measured with a vice and dial caliper, or else a spring tester. The latest info on valvesprings is run'em close to coil bind, like 0.050" more than solid height. That's for rpm engines. For our street engines the seat and valve open loads are much more important as long as you don't get within 0.060" of coil bind.

You notice I didn't use the term "seat pressure"? That's because its a wrong term. Pressure is measured in pounds per square inch or foot or whatever unit of area. Force per-area.
However the majority of the automotive world calls it open pressure or pressure over the nose or whatever pressure. So I may use spring pressure myself but I'll try to use words like force or load.

More coils usually means lower spring rate.

R.

Are you feeling lucky really
AKA aside, it is way better to have those springs checked on the heads and know exactly what cams they will work on properly and go from their