sorry, I know it's a horrible excuse but my car decided that it didn't like to cool itself any more, so I was kinda busy with that.
Hopefully it's just a bad thermostat and no engine damage occured.
To answer your question...
All it says in the book is that "A warped cylinder head can be machined provided no more than .3 mm (.012 in) of material is removed. If further machining is required, the head should be replaced."
It has a picture of a head with a straightedge and a feeler gauge that is labeled "Straight edge and feeler gauge being used to check straightness of cylinder head gasket surface"
I don't see any variance for how straight or tight the straightedge needs to be across the top of the head.
There is a chart that has the max and min measurements for the height of the head (before/after machining)
Sorry I couldn't be more help.
'86 325es (TURTL3): PJ peetsa hawler
'87 535is (BADWATER): almost done... really.
'86 325e (GRN HLL): DD/show/rocket
'04 x3 3.0i: Wife's Bimmer (manual, woot!) My BMW Blog
Last edited by ldsbeaker; 01-30-2008 at 11:45 AM.