VALVE STEM-GUIDE CLEARENCE
Posted: Fri May 24, 2013 2:39 am
Author: RGH
Just getting the finishing touches done on my A4 head, 1st over size stainless steel valves (stem 6.95mm) with new bronze guides (I know, shouldda used those sleeve insert jiggers) is 2 thou for inlet and 4 thou for exhaust OK? 1015cc standard cams -climate a bit hotter in Oz.
Thankz in advance.[/quote]
Posted: Fri May 24, 2013 11:51 pm
Author: Garn 1
RGH, I think you may have made a mistake regarding "1st oversize SS valves"...... Is this size relating to the OD of a bigger valve head or the stem? As far as I know, the Z1- Z900-A4 only have the one size stem and that is about 6.95mm (nominally 7.00mm).
The valve guides do come in various oversizes up to 0.004" (0.1mm).
It is important, if the guides have been reamed or replaced, that the seats are re-cut, albeit lightly. I have only recently found out that the valve-guides do distort when pressed in and when finally reamed can throw the valve well out of its concentric position. Valve lapping will immediately identify this problem.
Your exhaust is probably on the limit, however, would be acceptable with your new valves & guides.
RegardZ.