A valve grinder is a tool used to smooth the valves of an internal combustion during a comprehensive engine overhaul.

Manual suction cup valve grinders usually consist of a shaft with a rubber suction cup at one end. Or in many cases two different sized suction cups, one at either end.

The suction cup is placed on the valve head and the valve is pressed into the seat. By rotating the shaft by rubbing it between the hands, it will grind the valve into its seat.

Valve grinders are always used with an abrasive paste which is used to smooth the valve face. This paste comes in both coarse and smooth grades.