Comments: All the webers run the same... I have a Weber 34/34 and put together a nice thread on how to tune and change jets. I would recommend the Weber 34/34 or 32/36, the 38/38 is too big a carb for most of us and is not progressive venturies. ON the 38/38 both venturies are used all the time.
I agree this is a nice upgrade for 1 or 2 barrel 4.2 liter jeep. Works realy well with correct jets, more power, response, and 24 mpg. Webers like a better ignition so do the TeamRush, aux grounds, and CDI if you can. Here is a link I put together for a good jet change and tune information. http://www.jeepforum.com/forum/showthread.php?t=631105