Weber carb tuning

I want to get my Weber 34/34 carb running a little more fuel efficiently. Is there a way to play with it to do that? My friend was the one who suggested the Weber and told me they were able to be played with for either a lot of power or a high gas mileage? I'm guessing it would be the Idle Mixture Screw, but I don't want to mess with it without knowing a little more first.

The other question I had was that I was having trouble tuning my carb when I reattached the throttle cable. I had to disconnect it to take off the valve cover because I needed to weld shut a crack. I finally got it running about right, but I can't turn on the AC without my rpm's dropping about 500. Is this normal on the trucks? I've only had the truck since November and I got tired of fighting with the heat here in Texas. So is it normal and I should just set my idle higher to counteract this or is it something wrong?

Mixture is a good start to making the carb more fuel efficient. Then, make sure your timing is on right; 6 degrees BTDC. After, you can play with your jet sizes to give you more fuel economy...

Take a good read on my techie about it:


Another thing is, you need to really make sure to have your engine maintained in the first place! Good maintainenance is key for best MPG.

I'm not too particularly sure about your low idle with the AC, so I'm not going to suggest anything.... Higher idle would be okay. But how much is the question... Your idle should be 825. This is with some load on, though. In my case, I have my idle at almost 1000 because of my sound system. I suspect the reason for the low idle is because of the computer had some control over that...

Anyhoo good luck, and welcome to the world of Mazda trucks!