The valve spring seating pressure on a stovebolt engine is so low, along with the moderate cruise RPM and type of use most of these old rigs get, that hard seats are not really necessary. Now, if you intend to run full throttle for miles at a time with max gross weight, that's a different matter. If you want to add a bit of lubricant to the valve guides, run a 5% mixture of Diesel fuel at every fill up- - - -1 gallon of Diesel to 19 gallons of gas.
Jerry
