Hello all...I am a new member of the forum and a new owner of a 1966 Dart with a 225. The car has some great family history in California, but I have taken the car with me to live in Colorado. I am looking for an idea of where to begin on jetting. The car has the stock Holley, with headers being the only mod I am aware of. Anybody have any thoughts or ideas? Thanks!!!!!!!
Slanted66

Well, I lived in Denver for over 20 years, at 5500 feet. That tends to want a smaller-than-stock jet. But, headers (eek, why?) tend to want a larger-than-stock jet. So a stock jet might be more or less correct. Have you read the spark plugs yet?

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Too many people who were born on third base actually believe they've hit a triple.

The headers came with the car...I have not yet read the plugs, but can tell it is very rich.; I was hoping somebody would have a chart, but I might have to just dive in and make small changes. Thanks for the help!
Slanted66

Well, I jumped in and started making changes this weekend. Went from a 62 to a 55 main jet and the car runs great! A plug check (after installing new ones) verified the jetting.
Slanted66

Good work, a #55 should be about right. (a #62 is pretty rich, even at sea level)

Drive it and see if you get any surging at high rpm - light throttle cruise, that would be a sign that it is lean.
DD

Thanks Doc...No surge...Sure did make it more fun (and less stressful) to drive!