Supertech valves collets groove

[Radugns]

Hello,

I am working on a turbo engine (mk2 clio) and is the time to look for new valves. I read some posts on youtube and find out that collets groove are a bit up than standard valves? That means the springs are not so much compressed?
Does anyone know by how much are up? To can add washer under stem seals. I can measure after I got the valves, but really want to get all parts once.
I can go with 197 springs or catcams springs. Can anyone help me?

Keep safe,
Radu

 

[incy-spider]

Hello,

I am working on a turbo engine (mk2 clio) and is the time to look for new valves. I read some posts on youtube and find out that collets groove are a bit up than standard valves? That means the springs are not so much compressed?
Does anyone know by how much are up? To can add washer under stem seals. I can measure after I got the valves, but really want to get all parts once.
I can go with 197 springs or catcams springs. Can anyone help me?

Keep safe,
Radu

I measured this, If I remember correctly it’s the 1.2mm shims from pure if re using standard springs

Valve Spring Shim

Valve spring shim washers for adjusting the pre-load and seat pressure of the valve springs. Available in 1.2mm, 1.0mm and 0.6mm thicknesses. To be fitted under the va

www.pure-motorsport.co.uk

I checked back through my emails


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[Radugns]

So even using 197 springs to keep the ratio of them I should get de 1.2mm shims. Thanks!!

 

[NorthloopCup]

Not quite so simple as that I’m afraid. You need to know the spring rate at the fitted length.

Look on catcams site and it will give you the info about their springs to give you an idea.

If you give the springs to much preload, it’ll hammer the tappets and sound like a diesel every time you start it.

 

[Radugns]

Not quite so simple as that I’m afraid. You need to know the spring rate at the fitted length.

Look on catcams site and it will give you the info about their springs to give you an idea.

If you give the springs to much preload, it’ll hammer the tappets and sound like a diesel every time you start it.

Basically the only think I want is to keep the standard spring rate as it was with standard valves. Using 197 springs is because I already have a 197 head that will be used on the turbo engine. Also helps me a bit with CR having same chamber volume as 250 megane, just use small gasket to be closer to 9:1 instead of 8.4:1 as megane 3.
So adding shims is just to be sure I keep same 197 spring rate as it was developed...
Theory tho...

 

[NorthloopCup]

I’m pretty sure that the super tech valves don’t fit in as deep on the seat as the originals do tbh, which would explain the collet groove being higher.

 

[Radugns]

I’m pretty sure that the super tech valves don’t fit in as deep on the seat as the originals do tbh, which would explain the collet groove being higher.

Just one way to find out. I have a spare of uncutted 197 valves, fit one in a head and measure the distance from a point to grove. Than in the same place fit a supertech valve and measure. If there is a different, I will add shims, if not leave it like so.
But if the valve don't fit as deep, should't this affect the CR?

 

[incy-spider]

Just one way to find out. I have a spare of uncutted 197 valves, fit one in a head and measure the distance from a point to grove. Than in the same place fit a supertech valve and measure. If there is a different, I will add shims, if not leave it like so.
But if the valve don't fit as deep, should't this affect the CR?

It won’t compromise CR mate


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[NorthloopCup]

It won’t compromise CR mate


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It does reduce the cc’s in the combustion chamber though mate.

 

[incy-spider]

When I did mine I measured in CC after they were cut against a standard head and I couldn’t see any noticeable difference.. mine were cut in though not just lapped in because my seats were quite pitted


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[Radugns]

Bot the most accurate measurements, but you can have an idea.
In the first picture I measure the distance from valve guide to valve collet with supertech valve fitted in and in the other with standard valve.
There is almost 1.2mm difference between them.
I am not sure if valves were designed like this or not all f4rs engine share the same spec valves.

 

[gambit]

What shims did you use in the end ? Also are the 197 balances one piece or two much like 182 valves?

 

[Radugns]

197 valves are the same as 182 valves. At least now the part number is the same.
I did not assemble the engine, but I think I will use 1.2mm shims