Many people seem worried about hardened seats. But Just for Information, my machinist with over 30 years experience, building engines told me that the originally Installed 1960's mopar seats are harder than any ford or chevy seats at the time. And, any new seats he would order for my engine today are no better than the original factory seats made back in the day. so, don't waste your money unless the seats are bad. I remember reading a mopar Direct connection magazine article in 1988 where Chrysler tested all the mopar heads, and engines regarding seat wear with unleaded fuel. The results were, on Heads run during the 60's and early 70's, that hardened seats were not necessary unless you exceeded 85% of the RPM band, 85% of the time.Personally, I have never had to put hardened seats in an original mopar engine. Chrysler did put even harder seats in later,(1972) because of Increasing emissions standards. So, if you have a bad seats, replace them, but don't make extra work for your self, Mopars are tough! In contrast,Ford didn't even put seats in their engines in those days, so I did a lot of valve jobs around 40k with them. On A side note, lead was added to prevent pre- detonation in 1914 or so, and valve lubrication was a side benefit.
