Maybe someone can help me figure this out.

Say I'm here in Tejas and will be going to Bonneville.

Here in Tejas were at 300 feet elevation.

Particulars are: 29.515 In-Hg = 1000 Millibar.

Bonneville is at 4219 feet elevation.

Particulars are: 25.78 in-Hg = 873 Millibar.

Correction factor for Bonneville

air temp and rel humidity for altitude

at 90 degrees F, 40 percent humidity = 1.085

So 873 * 1.085 = 947.2 Millibar

Temperature only correction factor

at 90 degrees F, 947.2 Millibar

(per deg F, add algerbraically)

add -.003 per degree for 15 degrees.

add a neg number is subraction:

-.003 * 15 degrees F = -.045

So we end up with 902.2 Millbar.

So how do I use this information for a standard holley type carb?

If I going from 1000 Millibar to 902 (say 900) Millibar,

Will my N/A car run 10 percent richer at altitude than adjusted here in flatlander country?

If so, how many main jet sizes will I need to change?

Is my logic correct?

Is there a correlation between jet size and Millibar?

I've been lookiing but can't find it.

Cheers,

Spike

REF: Pressure Barometer, Millibars, ML - 102 - D, U. S. Army Signal Corps, 17 - DAY - 44, FORM No.1766.

Manufactured by Wallace & Tiernan Procucts, Inc. Belleville, New Jersey, U.S.A.