While I agree with Tom's thinking, I would hate to jet it lean.
It would be nice to know some additional parameters: ie engine size, engine mods (especially camshaft and or compression), and what jets would have been correct for your 268 foot elavation.
Also would want to know if you are using dinosaur fuel or a corn mixture. Basically, the reduced energy content in E-10 seems to work out very well to 1 size lean (4000~6000 feet). But you are at 7000 which works out to 2 sizes lean.
So, I would put in 1 size lean (0.002) for E-10 fuel or 2 sizes lean (0.004) for gasoline.
And once you change the jets, change the spark plugs.
Jon.
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