Manual Throttle

[Firebirdjones]

Originally Posted by DnvrJay71

Would that affect driving around town at normal altitude? (5-7K feet) When i'm wheeling it's normally up near 10K

Yes to some degree. I live at 5,000 feet here, and routinely drive down to the valley (~1200 feet) and up over 8,000-10,000 feet in the mountains.

What cleszkie says about adding timing at higher elevations is true. Up here at 5,000 feet I can get away with 2-3 degrees of extra timing on the same octane fuel. Jetting also has to come down at higher elevations.

What throws me a curve ball is the dragstrip being in the valley at 1200 feet but I do all my tuning up here at 5,000 feet. There is about a .2-.3 difference in AFR readings on my wideband depending on the temperature differences.
Usually 2 jet sizes is enough to compensate.

After experimenting I've found a happy medium at 5,000 feet so I dont' have to touch anything when I go up or down in elevation. I just live with it being slightly rich at the high elevations, and keep the fueling near spot on at close to sea level. Some carbs are easier to change and tune than others.
The holley carbs with adjustable air bleeds (HP series) are the easiest for this type of tuning. I have one application of mine jetted near perfect, and simply swap air bleeds for altitude changes, makes it quick and easy.