Matching Valve Springs To A Motor

[camerondownunder88]

Hi,

Just in need of informatoin on how to match valve springs to a motor.

 

I have a set of dual valve springs off a 4K head to suit a K motor but I have been suggested by a person to not run dual valve springs as it is over kill etc.

 

So I know there would be a way out the how to calculate amount of valve pressure you would need when it is fully open and also seated shut.

 

So can anyone enlighten us on how to match valve springs to a motor and what to do? As I don't want to kill cam lobes or break parts of the motor from having to hard valve springs for the motor.

 

Cheers

Cameron

[tojo2]

By using double springs, the thikness of spring wire can be reduced to avoid coilbinding when using a high lift cam.

Increasing hardness of the springs is only nessesary for high reving.

 

 

From Crane cams pages :

Common Misconception:

Many people mistakenly think that using higher seat pressures causes a reduction in the horsepower delivered to the flywheel because higher seat pressures (and also higher spring rates required for high performance) require horsepower to compress the springs. This thinking is simply incomplete! For every valve that is opening and its valve spring being compressed, another valve is closing and its valve spring is expanding. This expansion returns the energy to the valve train and the engine. This results in a net power loss of "0" hp. Many engineering texts refer to this as the "regenerative characteristic" of the valve train. Recent tests at Crane have shown no horsepower loss on a hydraulic roller equipped engine when changing the seat pressure from 135# to 165#. Power actually improved significantly at top end, probably due to better control of the relatively heavy valves in the engine.

 

Use a good oil to avoid "killing cam lobes". Double row cam chain is recomended no matter what springs you use.

[KE30_KE35_KE55]

standard Toyota valve springs are fine as long as they are within specification, this is mainly a free height to see if the spring has sagged.

 

there is no benefit to be gained by upgrading in-fact it does load up timing chains ect.

[trd]

you need to know your installed height. measure the height of the spring installed, then you need measure lbs - to do this use a drill press & some bathroom scales. sit the spring on top of the scales & compress the spring to the height it was installed at. take the reading. from there you sould be able to work out what you've got. i think 85 - 100 lbs is about right. as for crane cams saying no power loss, bullshit. there test engine is probly a 454 big block not a 1300cc corolla engine.

[tas_ae71]

as for crane cams saying no power loss, bullshit. there test engine is probly a 454 big block not a 1300cc corolla engine.

 

quite possibly, they do tend to specialise in V8 engines.

[irokin]

as for crane cams saying no power loss, bullshit. there test engine is probly a 454 big block not a 1300cc corolla engine.

 

I totally agree. If thats the case...stick some 1000lb springs in there and THEN tell me theres no power loss. Its pretty futile trying to measure something like that on a dyno too... :lolcry:

[camerondownunder88]

Hi,

Been a bit slow to reply to my thread but here goes.

 

I also believe bigger springs you will lose power. It takes some energy to compress the spring. More energy is taken for larger springs. Now if the theory was right when you compress a spring one is closing that would mean you use 0 HP to compress the springs and umm how can that be there are losses, friction, and you can't get something for free the laws of physics just don't let us do it. So totally BS the crow cams page that says that.

 

As for the springs talked to my engine re builder and got a 800 page text book on performance piston engines and they all say the inner spring is added to be more of a dampener at high RPM and the extra load also stops valve bounce. They are best suited for cams running more duration than 270 degrees I have been told by both sources. So I think I will still use them. They came off a 4K head that was running stock valves and retainers so with my 5K the springs should go well. Just I don't ant to lose more power..LOL

 

Also TRD I will do the scales check and see what I come up with. But can anyone tell me the stock spring install height into a 3K head or a 5K head jsut so I can get a height as at the moment I don't have any of my K motors in parts to measure them up.

 

Cheers

Cameron

[styler]

What you have to do is match valve springs to a particular camshaft.

 

Generally:

 

Stock springs for a stock cam

Mild springs for mild cam

Heavy springs for heavy cam

 

Go to a cam grinder and get him to analyse the cam you are going

to use on the cam profiling machine, might cost $20 for a cam report.

 

Then he will recommend the 2 pressures, a seat pressure and a nose pressure.

 

Then comes the hard part, finding the springs.

 

What you want is springs listed for your engine with a chart of pressures at certain heights.

unfortunately sometimes springs are only listed by code or don't have a chart or are listed as

a general category ie stock, mild, heavy duty.

 

Then comes the fun part

 

Theres only 2 ways you can play with springs:

 

1) Different types of springs

2) Installed height

 

1) So choose a spring, get the spring chart for it and then "install" the

springs by the chart figures. You want to try and get the seat and nose pressure that

the cam grinder gave you.

 

2) Seat pressure comes from the installed height, the more its compressed the

more pressure the spring exerts. this is done by using different thickness shims

under the spring. Most shims come in 15, 30 and 60 thou in a range of ID and OD

sizes.

 

Nose pressure comes from installed height minus lift, ie the cam lobe rotates and now

the nose of the cam lobe comes around and compresses the spring even more.

 

Why its fun is because the seat and nose pressure are always a compromise as you can

only adjust one thing, the installed height.

 

So

 

More seat pressure = More nose pressure

Less seat pressure = Less nose pressure

 

You can:

 

1) Get either one dead right and the other one will be a bit off

2) Compromise on both and have both slightly off spec

 

Now the recommendations by the cam grinder are a guide

and don't have to be exact which would only happen by pure

chance anyway and springs can be a bit off per batch as well.

 

So obviously the compromise on both is the better option,

and you just play around with the installed height until

they are both off by the same amount or whatever you like.

 

As i said before the hard part is finding the springs listed by

motor with charts.

 

One point to be aware of is that double spring specs are listed as flat height, ie no step in the retainer,

most retainers have a step to locate the outer spring which has height to it, so basically the inner spring

will be more compressed than the outer, leading to a higher overall reading to the specs listed. This can

alter listed specs up to 20% higher for both seated and nose pressure. Sometimes different inners with

a lower pressure may bring this down but its difficult to find ones to suit the outer and the retainer.

Edited January 19, 2015 by styler