Rebuilding your John Deere or Perkins cylinder head? Here”s a no cost way to extend valve spring life. Simply polish each end of the valve spring in a figure eight motion with 200 grit emery paper. This works especially well on cylinder heads with two sets of valve springs (inner and outer) such as some Perkins and John Deere engines. On Continental flathead valve springs remember that the coils once polished must be placed with the end with the tightened windings pointed down toward the oil pan.