How much spring pressure is too much?

[73Scamp318]

I recently spoke to Lunati over the phone about one of their cams (10200705, the big Voodoo for a small block) and the set of Comp 987-16 valve springs I got as a gift.

With the 1.6 rockers I have on my Edelbrock heads and at a 1.800" installed height, the pressures work out to be 120 lbs closed and, on the exhaust, right at 340 lbs open @ .590" lift. I would expect that the pressures will be lower after it's all broken-in.

The Lunati tech said that was on the upper limits of what the recommend on hydraulic lifters, with their cap being 350 lbs, but he didn't think there would be a problem running it. He also strongly advised that I run a high zinc oil, which I was planning on doing.

Is this too much pressure for a street/strip engine? What would be a safe limit? Anyone run pressures this high on a street/strip flat tappet hydraulic? How did it hold up?

 

[crackedback]

Your actual lift at the valve isn't going to be the theoretical. It's likely going to be about .560-.565

That will give you a rate around 330 open

The spring lunati recommends is 115 at 1.700 and 336 at 1.150 with a 402 rate

That comp spring is 120 at 1.800 324 at 1.250 with a 370 rate.

The comp spring is really lighter than the one lunati recommends which is the same as a 995 comp spring.

 

[73Scamp318]

Thanks for the info, it sounds like the springs I have should work okay with that cam.

I guess what I'm asking is with the higher pressures, does the cam and lifter set turn into a wear item, where it will need to be replaced every so often? I'm assuming that it breaks-in okay, I use the recommended oil, and don't end its life early by screwing something up.

 

[flyfish]

You should be fine as long as you break in the cam properly. Don't forget to remove the inner springs for the break-in process to give the cam a good shot at surviving.

And no to your other question...if taken care of, you should not be wearing down the cam fast. I would check it whenever you tear the engine down for a refresh (years down the road), but that's it.

 

[73Scamp318]

Thanks for the tip, I'll be sure to pull the inner springs for break-in.

That was what I was wondering about the life of the cam, thanks flyfish. :-D