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<x-charset iso-8859-1>OK... I hadnt been able to picture this in my head... it makes sense now! so long as the adjusters can take out the distance without changing the valve geometry. Berg explains that we actually create a hardness layer during breakin and is why breakin is so critical... I think there is surface hardness when the came is manf though. keith > KeithP=> how can it be possible to grind > => anything off the lobe and not significantly > => reduce the lift? > > That'd be the case if you only ground off high part of the lobe. But as I > understand it lift is the difference between the high and low ends of the > lobe, not the height of the lobe relative to the center of the shaft. > Regrinding generally takes metal off all the way around, and the adjusters > make up what gets ground off. Given enough meat to start with you could even > increase lift with a regrind by taking more off the low end. > > But the thickness of the hardness layer is always mentioned in any talk of > regrinding a cam, and I think that's the main problem. It probably never > mattered with the older engines (flathead Fords, say) and their pretty basic > metallurgy, so regrinding became a pretty common tuning procedure. > > (I idly wonder whether it makes any measurable difference that a ground-down > cam lobe is moving a bit slower relative to the lifter ....) > > Steven Ayres, Prescott AZ > '66 Grosse Karmann > > ------------------------------------------------------------------- > Search old messages on the Web! Visit http://www.vwtype3.org/list/ > > </x-charset>