Tech: Valvesprings

shiroitenshi

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Well, this is another random tech article. Its not really a big thing since nobody installs their own vavlesprings, but here are some stuff I learned.

Valvesprings usually has its own spec sheet, they are not usually published online, but you can request them from the manufacturer. Most US valvespring makers have them on request.

Terminology you need to know.

installed height:
This is how tall the valve springs are after they are installed. The install height is different due to the valve seats. usually there is a small difference. as long as its within 0.5mm, shouldn't matter much.

why is it important:
the installed height preloads the spring, this gives you "seat pressure" that means how hard your valves press on the valve seats.

seat pressure:
This is how hard the valves press on the valveseats. For lastability, we don't want it very high, because it stresses the valvestems. but for turbos, we want it high enough so that it will close properly against the flow of air rushing in from a turbo or supercharger. We can't really change this springs to spec, but we can change valves seats and grind them to get the seat pressure we want. The springs specs usually have seat pressure vs install height table. Too high, and you risk breaking your valves even if you have good clearance.

coil bind limit:
this is usually the limit where the valvesprings bind. Means if you compress it past this limit, it wont return back to its original height. Most aftermarket honda is 19mm+, but take this with a pinch of salt, the older and worn out the springs, this number is reduced a lot.

Thats all I remember for now, its something to pay attention to if you run aftermarket cams. They are WEAR & TEAR items and need to be replaced from time to time.



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Izso

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Interesting. Valvesprings are one of those things that last for the lifetime of the car too yes?
 

shiroitenshi

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Interesting. Valvesprings are one of those things that last for the lifetime of the car too yes?
edit: just understood your question after rereading. wear for valvesprings is possible. the more fatiqued they are, the lower the coil bind limit will be. if your coils bind, the keepers will pop out and you will drop your valves.

I don't know if there are ways to identify a failing valvespring till its too late. so far I follow the is change them when I need to replace the piston rings rule. Its cheap insurance for a built engine.

Maybe only if you run standard cams and springs, but they do wear. so once you get to a very high mileage, you'll probably start seeing it or have failure. Most of the time, already changed car at that time.

Aftermarket is even faster wearing, so its something to think about if you're on aftermarket cams

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Last edited:

Izso

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edit: just understood your question after rereading. wear for valvesprings is possible. the more fatiqued they are, the lower the coil bind limit will be. if your coils bind, the keepers will pop out and you will drop your valves.

I don't know if there are ways to identify a failing valvespring till its too late. so far I follow the is change them when I need to replace the piston rings rule. Its cheap insurance for a built engine.

Maybe only if you run standard cams and springs, but they do wear. so once you get to a very high mileage, you'll probably start seeing it or have failure. Most of the time, already changed car at that time.

Aftermarket is even faster wearing, so its something to think about if you're on aftermarket cams

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Awesome!

Ok in that case it's probably time for me to source for a set. But need to understand the differences in stiffness and how it'll affect my cars performance. I've been re-reading what you wrote and comparing it with what I can gather online and gah.. it's just too much info.
 

shiroitenshi

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Apr 18, 2006
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Awesome!

Ok in that case it's probably time for me to source for a set. But need to understand the differences in stiffness and how it'll affect my cars performance. I've been re-reading what you wrote and comparing it with what I can gather online and gah.. it's just too much info.
well I simplified it. There is no 'correct' seat pressure. the more aggressive the cam in lift, the higher those seat pressure needs to be. since some people are cutting their valveseats (i see nasty port got a serdi machine) so it may be a concern fornthose running boost, as cutting the valves do reduce seat pressure somewhat. but turbos don't usually run aggressive cams.. they need to worry that at high boost, the valvespring will have enough pressure to close against the air rushing in from the turbo.

Its also a good info if you mix and match like crower valvespring retainer paired with a skunk pro 3.
you need to know the limits of the valvespring
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