I should have said that I am not including ethanol gas as I only run non-ethanol. I wasn't really thinking about built up engines as that changes the formula altogether.
Surely the gas is not the same today as back then but octane should be the same.
The previous threads are what got me to thinking about this question.
Octane is NOT rated the same way today as it was in 1965. A T or C code engine will run quite happily on modern regular unleaded. Set your timing for 36 degrees total advance and run the lowest octane fuel that doesn't make you engine ping under load
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