To find max lift, do you subtract open height from installed height? Does that mean these springs are good for .850 lift?
http://ebay2.ipixmedia.com/abc/M28/_EBAY_87a241ced0fdeb340f6e2157d0f7c583/i-3.JPG

Also, what spring pressures do you need for a solid flat tappet cam revving to about 6500?

I know the cam manufacturer recommends certain springs with each cam, but I haven't picked out a cam yet and I am sending the heads out for machine work...

I definitely wouldn't buy springs before the cam... you need to match the spring rate to the required spring rate of the cam.

for example my springs for my comp XE262 are about 425 lb/in.

also the spring pressures they give you are just a means to calculate the spring rate which is pounds of force per inch. in this case it's
(794-280)/(2.1-1.25) = 604.7 lb/in

the solid height they give you is the coil bind.

here's a site for ya: http://www.mrgasket.com/images/ads/tp098.html
check the last entry in the chart near the bottom


------------------
1968 Coupe (http://www.eden.rutgers.edu/~vath/Camaro/), 327/210hp project in process. PS/PB, Factory AC, adding camelhumps and a CompCam XE262
1986 Chevy Stepside (http://www.eden.rutgers.edu/~vath/Stepside/), dying 4.3L, TH-400, no A/C, 2wd, 1/4 million miles.

[This message has been edited by JIM68 (edited 01-16-2003).]

Well, I've been perusing the cam charts, and I am leaning toward one of these three:

XR274R
XR280R
XR286R <-- getting my preference so far...

Don't buy springs if you don't have your cam picked out. It's too important of an item to just take a swag and go for it. Use the exact spring installed at the exact height your cam manufacturer recommends.

When looking at the spring catalog they usually include:

OD (outside diameter) your valve pockets need to be at least this size.

ID (inside diameter) Your valve guides have to bee smaller than this spec.

Installed height - the distance from the bottom of the retainer to the surface of the valve pocket. you have to shim the springs to get the correct height.

Seat pressure - how much pressure the spring has with the valve closed when the springs are installed at the correct height.

Load at checking height (or load at open height) - how much pressure the spring has when the valve is opened to the spec height. (installed height - check height = how much the valve is open)

Coil bind - the height at which the spring binds. Installed height - bind height = valve lift at coil bind. You don't want your lift to be EVEN CLOSE to this number. Spring pressure starts to go way up when you are close to coil bind. .050" is generally considered as close as you should get to coil bind.