340 X Head Value

Dartswinger70 said
I agree with this. My machinist told me "If you aren't hard running it daily you'll be ok without hardened seats " But you are right it seems to be an old topic not heard much of lately and its brought up here to discount the value of the X heads. They hold their value as do the j's If they aren't worth anything they'd be cheap and people would be buying them up. There isnt 1 318 guy here that would pass on a set of them if they were cheap.

You are spot on. Dyno test show run an engine at 6000 rpm on dyno for weeks months on unleaded and valves sink. Do the same with leaded fuel or hardened seats they don't sink. So now everyone thinks hardened seats for unleaded are mandatory when 99 percent of engines aren't run full throttle non stop like that.