masterx81

iTrader: (4)

Hi to all...
Someone know, please, the min and max shims that can be found for the v3/v4 sti heads?
Maybe can be nice also have the subaru part number of that shims, as here in italy no sti classic models was imported (doh) and the local subaru dealer dont' know how to search them.

I've done some work on the seats and now i think that i've gone a little too far on grinding (lowered the exhaust valves for limiting the charge loss trough the exhaust during overlap).
I've also measured shimless buckets for late models, but are 2.20mm to tall and 35mm in diameter while v3/v4 are 33mm.

Really thanks!!!

merlin24

iTrader: (1)

Common problem when re-cutting the valve seats and valve face.
IIRC, the smallest shim is 2.00mm and the largest is 2.70mm.


Mick

masterx81

iTrader: (4)

Doh... Only 0.70mm of allowed regulation???

Maybe i can try to get machined some shims, the underbucket type seem that not have any superficial treatment (while the over bucket are heat treated for obivious wear reasons).
I've lowered the exhaust seats of about 1.1mm, so if the shims are in the 2.00 to 2.70, i need some 0.90/1.60mm shims... Doh...
Else i can grind my cams by 0.5mm for recovering the space, and gaining some lift (v4 sti cams).

Maybe did you know the subaru part number of this shims?

Really thanks for the help!!!!

masterx81

iTrader: (4)

Maybe someone know of what steel alloy is best to machine the shims?
Chromemoly 4140 will be right?
Thanks!

masterx81

iTrader: (4)

So no simple solution for me?

carpboy

iTrader: (2)

Was told by a respected engine builder that its possible to grind the stem of the valve to get the clearance.

merlin24

iTrader: (1)

You can "tip" the valves to gain some clearance but wouldnt take 1.1mm off them tbh.
The OP would be better off getting some 'top hat' shims (similar to the STi Version 2 RA) from Kent Cams.
IIRC, they are 5mm thick and can be linished/machined to the correct thickness and then hardened afterwards.


Mick

masterx81

iTrader: (4)

Yes, this is possible, but i have already under the hands a set supertech valve (ssinlet and inconel exhust), with hardened tipo, and if possible i prefero to find some other ways to slove the problem

Actually 1.1mm is possible grinding the tip (up to near 1.7mm before the top of the stem will run under the machined surface of the retainer), but if possible i prefer to save the pricey supertech valves
Also using the overbucket shims is possible (they are more thick), but i know that on v4 wrx, over 7500rpm this can be broken (or spit out) by the excessives forces, and i'll hope a little bit higher redline (8000, like the sti). Plus, the overbucket setup will weight near 6gr more that the sti setup, so i need more stiffer valve springs.
I'd suppose that the underbucket shims will not be made in less that 2mm because there is the risk that after the hardening, the material can be too brittle, also using case hardening.
I've asked some info here:
PRECISION SHIMS AUSTRALIA | INLET SHIMS | EXHAUST SHIMS | VALVE SHIMS
And i'm waiting for the response.

Sorry, but how is the 'top hat' setup of kent cams? I've not seen this setup on the kent site! They uses some sort of lash caps?

I've also the facility to machine my own shims (I have a friend with lathe and mills, cnc and manual), searching over the net seem that they are made from 4140 steel, then case hardened.
I know a factory that can nitride things (with small moneys ), maybe instead of case hardening i can try a nitrided surface?
The nitrided layer don't change the properties of the steel, but add a hardened layer...

Really thanks for the help!!!

masterx81

iTrader: (4)

Someone can, please, pm me a v3/v4 sti VIN number? They uses the same shims underbucket.
The local subaru dealer isn't able to get the part number of the shims, because here in italy the sti model was imported only from the v7 version, no classics sti, only wrx, doh...

Really thanks!!!