If you want to expect any life expectancy out of your cast iron head, do your head
a favor and install these hardened seats during your rebuild. These seats will not
only dramatically reduce/eliminate the likelihood of your head cracking in the future, but
will help "patch" any very small cracks already developing around the seat area
that you cannot detect with the naked eye and sometimes can't with a magnaflux.
These are sized for 1.59" or 1.60" exhaust valves and are made of a Rockwell Rc45 hardness rated nickel based alloy designed for extreme temperatures and hot hardness
to 1600 Deg .F (Price is for set of 4)