Review on Permatex 80037 Valve Grinding Compound by Brad Collins

Works great for lapping valves on an Onan B43G engine. The label doesn't say what grit it says on the label, but according to Permatex, this mix starts off with a coarse grit, and as it's used, the grit gets finer (larger particles are removed). You can hear the difference when grinding the valves - the sound becomes less "scratchy" over time. Don't unseat the valve when you are nearing the end and want a finer finish as the coarser grit will come back. Be careful using a drill to speed up the process as you may end up removing too much. valve material if you are not looking.