Carb question

[red_dog007]

I am still learning a lot about carbs, and am about to learn some more.

I know for carbs, elevation matters depending on what elevation it was tuned on but I do not know when elevation starts to matter.

I happen to live in a valley that is roughly at 600ft above sea level. I am surrounded by AWESOME driving, but it is all up in the mountains ranging from 1000ft to I would guess 2000ft above sea level. I would say that most of it is at 1600ft, but all of these are rough estimates.

Now when I tune my carbs at 600ft, how much performance difference would I see going up 1000ft?

I know that in my buddies Bronco and my brothers FJ cruiser, going from 600ft to above 4000ft does take a little more for the engine to start, and does loss a bit of power, yet still runs very nicely.

That though is a 3000ft + difference. What elevation increase do you have to get to until you notice a difference in carb performance?

[hd240z]

I doubt you will be able to tell a noticeable change in performance going from 600 to 1000 feet elevation even though the air density will be slightly lower. Probably some of the real race car guys have the formula for that.

I remember that I used to adjust my SU's about 1/2 turn leaner when I would get to Colorado to compensate some of the thinner air at 5,000 feet and higher. Even with the adjustment the performance loss was very noticeable at that altitude.

[beandip]

I also live at lower elevation around 350' . We are surrounded by two ranges of mountains but the driving in them is in the 3000' area. There is a small loss in power but not much . As far as starting , you will find that you need less choke as the thinner air richens the mixture . As for adjusting the mixture to a leaner setting . I would only do that if you were to move to the higher altitude to live. Certainly the difference for driving while on a cruse isn't worth the trouble. I am using 54 needles and if I were to move to Denver for an example I would most likely change to 58 needles wich are leaner and go from there . Gary:)