Setting valve spring heights?

[Jeff Stout]

When setting valve spring heights for example all springs set at 1.90. Do you set them that way or based off of difference from intake to exhaust lifts. Say 500 intake and 480 exhaust. Do you ad 20 to the install height of exhaust spring to make it even pressure wise against cam. Or is there more to it then that?

[Dwight Southerland]

More to it.

[FED 387]

I set em straight across at 1.90 or whatever the installed height should be--FED387

[Tim H]

Originally Posted by FED 387

I set em straight across at 1.90 or whatever the installed height should be--FED387

We do also ...

[Dave Noll]

Originally Posted by FED 387

I set em straight across at 1.90 or whatever the installed height should be--FED387

Thats what I did as well

[Glenn Briglio]

Originally Posted by Dwight Southerland

More to it.

Did you check every valve spring or are you assuming they are all the same?

[Paul Precht]

I check each spring and put them in about 4 groups, if they're double springs I mix the weaker with the stronger. Your spring heights will usually have a variance like the springs so I mix the weaker springs with the tighter spring heights and hopefully require as few shims for correction as possible.

[nolongerracing]

Most spring manufactures want you to set spring heights based off of coil bind heights. Take coil bind height, add .060, and add net cam lift to get installed heights.
IE. 1.080 + .060 + .500 = 1.640. It takes a lot of searching to find the correct spring.

[FED 387]

basically what paul and nolongerracing posted---You don't just take em outta the box and slap em in---try to get springs that match up as far as tension and the least amount of shims to prevent a narrower dimension for coil bind--then box them up in sets--- of course you did all this before you got to the track while you were sitting around at home....FED 387

[Tom Meyer]

Back when I raced I would find the 8 best springs and put then on the intakes other 8 on the exhausts, it always seamed that if I broke a exhaust spring the car never slowed down. But with todays more radical cams and close piston to valve I would maybe rethink this. Installed height is what the manufactures recommended for that spring for wide band of different cams lifts. However my thoughts are to tailor them to your application, taking into account seat pressure, cam profile, and how close you can get to coil bind, to eliminate spring harmonics. Nascar has a lift limit so there cams are set up loft the valve to get more lift. You also have to have enough pressure to keep it from floating. Spring technology has come a long way over the years and we have adapt to it. All the time spent on cutting ring gaps and setting bearing clearances should not your valve train be included in your blueprint to making the best engine you can? Wow did I just write that. Tom