interesting....seems what i have gathered about this hardened valve seat is the problem lies in WEAK valve springs, not the seat...I know many engine builders who dont install hardened valve seats on the exhaust that have over 100,000 miles on there shop and personal vehicles that dont have these seats....seems they have learned its not the head material or gasoline that is the problem but using weak valve springs is the problem, this causes the valves to "bang/jump" around and pound in seat .....Interesting huh!!!???...I have talked to Ferrea valves about this and say say their research had seen this occur also...also from what I have gathered , Chevy/GM hardened the seat metal on the Chevy 250/292 later heads-so no installed hardened seat will ever be seen on a factory head, but of course they used very WEAK valve springs...I found this concept very interesting and when Ferrea valves confirmed my question about seat vs valve spring tension I was shocked...whatever works is great...give Ferrea a call....
Lee
