In Reply to: Re: I could be wrong (BUT) posted by TheOldHokie on July 23, 2019 at 14:05:31:
Well, at least I got an interesting topic started with the thread:). When unleaded gas was introduced in the 70's, we also did a lot of warranty valve, valve guide, and head work on Fords. Not only Fords, my Dad's new Chevy P/U burned two valve before it ran 10,000 miles. Whether you agree with me or not, you'll have to agree that the engines built from 1939-1964 (especially tractor engines) were not designed to run on unleaded gas. These modern engines today are with computerized EFI systems to regulate the air/fuel mixture based on temperature both ambient and engine, barometric pressure and elevation and timing variations will certainly give longer life to spark plugs and valve train components. The lead was in the gasoline to help dissipate the heat in combustion related components. The gap from the plug wire to the plug increase the temperature at the plug electrode to a point that it would fire the mixture.