Adjust Webers for altitude change

My "new" 2002 IM Roadster is being delivered today! It has a new CB Performance 1776 with 40 IDF Webers with around 1200 miles on it. The car has been in Bend Oregon at approx 3600 ft and coming to Dallas at approx 500 ft... Am I going to need to adjust the idle mixture screws to richen up just a bit for the lower altitude? I can rebuild a Holley 4 barrel without hesitation, but I've never even seen a Weber 40 and known what I was looking at :)

Chuck.........The first thing would be to get Tomlinson's Weber Manual from C.B. Perf......

This will get you through almost any situation concerning the carbs themselves......There are jetting charts that will give you a "starting" point.....But as the car is probably running well, it will probably boil down to air correction jets......

I have run the same jetting settup from sea level to 5,600 ft. with no problems.......Lane Anderson has made this same run, along with many others, and it just doesn't seem to be that big a deal.......

Hope this helps, and you enjoy the car for a long, long time...... ;-)

Yup, sea level (actually 10' above) to the top of the Cherahola Skyway at 5600' - no issues and no desire to mess with a good thing. I'm sure I could tweak another couple of ponies if I really wanted to, but it doesn't seem worthwhile to me.

I chose CB Perf. for my motor partly because I live at roughly the same elevation as their shop. (Had jetting issues with Webers in the past). From the Sacramento Valley (26' above sea level) and through the Rockies (7000'), I noticed NO problems with my 44's.
Hope this helps!

For what it's worth. I'm using the HPMX 40's. Jake determined using his dyno, that I should have main jets of 1.25 (that's 1.25 MM, commonly referred to as 125's) at 3,000' amd 130's at 550' which is my altitude MSL. Same air correctors for both altitudes.