Carb Jet Question ??

Any rule of Thumb for jetting based on DA ?

Ive been running in 2500-3000 foot air, now facing 200' so what should I be jetting up ?

I have found 1 jet for every 800-1000' change is that pretty accurate?

I am a bad plug reader...lol

Air Density Online is a pretty good resource. If your track is listed on their website then you can verify tuning data.

https://airdensityonline.com/

IIRC, that's pretty much what Holley says.

I use to race a LACR year round, it would go from 4300 Ft. density altitude in the mornings before noon and go to above 7300 Ft density later in the after noon during July and August, I wouldn't change jets daily but I had the carbs jetted pretty lean for spring, fall and winter so most of my cars wouldn't change a bunch in the summer months due to density changes
My current S/P car runs on E85 and that rascal doesn't change any up here in Madras during the summer at 2500 Ft. above sea level form mornings to afternoons, E85 flat rock
The same jetting at Woodburn, Or (180 Ft. above sea level) ran 8.862 and 8.866 one hour later that morning in late July this past summer
I'm not chasing ET so as long as it repeats I'm happy

Every combination is different and every fuel will have different requirements. For a guy who runs in really good air like you do I would say most your DA swings are due to temp and grains/VP. I would say for "normal" race fuel 6-800' would be where I would look to change something. Out here we can have huge DA swings from track to track due mainly to elevations. And that is an entirely different animal we will see ACTUAL barometer readings anywhere form 29.8-9 to as low as 25.6. Trusty me 27.6 baro (Vegas number)DA can be the same as 29.8 baro DA but you will need a completely different tune up to run. A lot more to the DA than a simple number but for you east coast guys the barometer is always good from what I've seen