Material for valve guide

[Horst Apfelthaler <Horst.Apfelthaler@xxxxxxxxxxx>]

Hello,

I'm currently rebuilding an M20/B25 head ('88 325i) and noticed that some
valve guides are worn.
The problem is that I can't get new guides in the required diameter because
somebody 
already did a head rebuild.
So the only thing is to machine the guide myself.
Problem: what material should I use. 
Some sources say CuZnAl is used, other rebuilders use bronce.
Does anyone have specs for this material?

Regards

Horst from Austria

'80 323i project car
'89 320iC
'95 A4 Tdi

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