cossie head
18-12-2006, 05:45 PM
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the minimum thickness is all determined by how much meath there is between the edge of the valve seat and the head - below 138.68 - there is vitually no metal and you have actually ate into the valve seat area -
i see what you are saying - if Nat Asp, you could get away with it, maybe as you are not running any where near as hot
i see what you are saying - if Nat Asp, you could get away with it, maybe as you are not running any where near as hot
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19-12-2006, 01:40 PM
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Originally Posted by TF Rallyesport
they are fine down to 138.4,a group A car is down to 137.8 and work fine,
dave do you know for a cvh rs turbo head?
20-12-2006, 10:16 AM
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interesting subject. when the head has been skimmed to 137.5 like mine you can see the valve seat inserts on the head face. some tuners say this is likely to cause the seat to become loose and perhaps fall out with disaster. other tuners say that the only issue to consider is the change in comp ratio and the seat in the head face is no issue. had this discussion with several very well known tuners and they fall fall into either camp.
another view from a well known engine builder is that the skimming removes the hardness from the head face. since some say its ok i'm happy with mine but when it gets lots of right foot it does sometimes come into your mind when you should be concentrating on braking instead
another view from a well known engine builder is that the skimming removes the hardness from the head face. since some say its ok i'm happy with mine but when it gets lots of right foot it does sometimes come into your mind when you should be concentrating on braking instead
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