Some say you need hardened valves but then you hear of folks who have drove their stock motors for years on gas w/ethanol in it w/no problems. I have never had a problem w/any older motors I have ran w/ethanol base fuels. My brother drove his 39 Dodge as a daily driver & would put 1000 miles plus a week on it w/the stock motor & drive train w/out any problems what so ever.
A lot of it has to do w/the amount of nickel in the block & how hard the motors life has already been. If you're building a fresh block then by all means have hardened valves installed in the head...joe
