Backfiring and popping in carb.

74EMPI · Post by **74EMPI** » Mon Jun 25, 2001 10:00 am

Hi,
I have just installed a set of 34 Weber ICT's. The carb for cylinders 1&2 is popping and backfiring pretty badly. Is this an issue of timing, jets or poor tuning? Also what screws do you set to adjust these carbs? This is my first attempt at dual carbs. Any advice?

Rouser914S · Post by **Rouser914S** » Mon Jun 25, 2001 7:01 pm

I'm not familiar with ICT's (I have 44 IDF's), but your carbs are definately not in sync (NSYNC?). You have to make sure the throttle butterflies on both carbs are initially set identical, and that the linkage you're using is pulling them both equally, or all bets are off.

You also have to pull the plugs on each side (cylinder pair) and see if you're running rich/lean, than adjust accordingly. It's a time-consuming hassle, but once set it should last till the next/future rebuild.

mtz49 · Post by **mtz49** » Sun Jul 15, 2001 5:05 pm

I use to have the same problem with a 1641cc that had ICT. You nee do set the timing first, then undo the linkage form both carbs. (use a syncronizer) Then one at a time adjust. start with the right side. If i'm not mistaken their is only 3 screws to adjust. Gas, air mix, then idlescrew. Remember that your going to have to mess with the linkage so that BOTH sides are opening at the same time, after you have adjusted the carbs. IT takes a lot practice to get it correct. the best time to asjust is when you give your engine a tune up. and remember that after you break it in, you might have to go back and give some screws a little turn (open or close them). If possible go to someone who knows how to adjust carbs and watch how they do it, so next time you'll know what to do.