Hello! maybe a similar topic has already being written but i want your opinion about the best fuel economy! i have a 4k-u engine with a weber 32/32 dgv! i want to ask you what kind of carb to use for economy! the stock one 28/32 or another brand new weber 32/34 that i have? i am thinking of the weber because it's new!!! what do you think? thanks alot!!!

the new weber is DMTL 32/34! thanks again!

You need to go down the same track as EvanG and fit an oxygen sensor & display. That will get you the best jets for the 32/32 to start with. I don't know enough about the downdraught Webers to tell you if one is better than the other, but in the end they all just mix fuel with air. Check his posts about it.

 

I've fitted a pair of oxy sensors to check each of the twin SUs I run, and use them for selecting needles and adjusting them. 7.5L/100km at 100kph... and it gets there much faster than stock!

ok but does a new one with it's butterflies open and close tightly is better for tuning and economy? just a question?

If you have a new 32/34 you should use it over an older carb for sure. You'll spend nearly all the time driving on the primary choke and they're both 32s. Get it jetted for economy with a oxy meter.

 

If you had to buy a new Weber over an old one it would be a bit more debatable. The worn throttle shaft lets air in at idle and leans it out, but they can be replaced anyway.

 

Here's a good read-

http://www.underexposed.org/weber.pdf