I've been looking at valve springs on comps website but I'm not sure which specs are important in determining if a particular spring is enough for the cam I want. I'm running 987's and I want to run a .560/.577 or an xe high lift .605/.622 lift.

 

If you're going to run a cam with .622 lift, then you want springs that can handle AT LEAST that amount of lift, so you'll probably want to look for springs that can handle up to .650" lift.

 

Look at the installed hight and subtract from it the coil bend, if the result is 0.05" more then the cam max lift then you should be fine in the lift. The pressure is also important in how the springs will control the valve at high rpm.

 

Call the cam maker and get their recommended spring for your cam.

 

Not only do you need a spring with enough lift capacity, you need one to control your valvetrain at the revs you want to run. That's at least as important as lift capacity.

Some cam guys are going to recommend a beehive, some aren't. Contact one or more opf them with all your engine specs and desires. They'll need more info than you've given so far. At the very least ask the Comp guys as 1racerdude suggested.

 

Thank you for all the responses, I did contact comp and they did tell me how to check the max a spring can handle. I've decided to go with the .560/.577 lift cam. My 987's I already have installed are enough to handle the lift and like you said I need to be able to control the valve at rpm. This is a FI engine. I'm finding out now that I need to run a spring with at least 130lbs seat pressure and 350lbs open pressure. My 987's seat pressure is only 121lbs @ 1.800 328 lbs open pressure @ 1.200. I've been looking at comps site for a while now an the only spring I can come up with is that meet my requirements is the 977 spring. It has a seat pressure of 155 @ 1.8500 419 lbs open pressure @1.250 and a coil bind @ 1.195. So when you do the math this cam will support a ~.595 lift cam.

The only problem is comp said that the open pressure would be too much for the stock hydraulic lifters. Do ya'll agree? I'm only reving the engine to 6500rpm. Also the 977 is a 1.460 diameter spring compared to the 1.430 987 so I might need some machineing done on the head to make them fit.

 

I'm not a cam/valvetrain designer, but I've seen a lot of them recently. Where did you get your 130/350 numbers? If those were for non-beehives, they might be a tad higher than your valvetrain needs for 6500. Yeah, I'd worry about the lifters @450#.

Contact a cam designer with all your specs including boost. Your solution might involve less machining than you imagine.

Also, read David Vizard's 10 page article in the current Popular Hot Rodding.

 

Those spring are non beehive springs. They are a comp dual spring. Is there a big differance in 419# and 450# b/c the springs I'm looking at are 419# open pressure. Do I still need to worry about lifter collapse?

I have to go to home depot in a little while, stop and look for the magazine.

Thank you,
Justin

 

150/350 are about the limits.Look into the Beehives and do whatever it takes to install them. Ya will make more power with them.