Advice on dellorto setup

[richardincov]

Can anyone offer some advice on setting up twin dellorto 40's with 30mm chokes? I'm happy working with injection etc but have never set up carbs before. They are installed on a 1600 Zetec-s and the engine starts well, runs, revs but idles roughly. Occasional spit back through carbs, pops and bangs from the exhaust. Car is freshly build so can't give any info on driving with any load - really just trying to get a reasonable idle and pickup so that we can go to Rolling Road and have it sorted properly. Don't want to waste time and money on RR with basic setting up which we could have done before hand.

Idle jets are all set to 2.5turns open from fully closed, balance screw fully home to enable both carbs to fully close butterflys but front carb still draws less air than rear carbs - seemingly no more adjustment?

Ignition advance is 10 degrees, cam timing is correct and std.

Any help would be much appreciated.

[350matt]

Have you set up the carb balance with a meter? As this makes a very large difference, balancing by ear etc is useless. Once this is done use a 'Gunsons Colourtune' to get each cylinder idle fuel right

[accident]

i agree get a carb balancer even the cheapo nasty ones are better than nothing.
im not a fan of the see through plug but if something is way off you will see it.
i wouldnt worry about pops from the exhaust but if its spitting back through the carbs when warm something is wrong.
are u using modded cams?
what ignition pack?

[kevo]

The first thing with 40`s either dellorto`s or webers,Is the air flow..If possable ...Remove the air filters,Get yourself looking from the middle of the 4 chokes,Take note on part throttle,(see if all 4 flaps are evenly open the distance from the bottom of the casting to the flap)If not Adjust the adjustment block in the centre that connects both spindles...Untill the flaps look ALL the same(down each venturi..You could do this by a tube and listening to the air hissing..But this is reliant on the compressions been equal)Then after the airflow`s the same Try the car.It may only be this wrong....IF things dont better,Very carefully screw the little screws with the spring under them (4)Thats on top...In untill thay stop...DONT FORGET TO COUNT THE ROTATIONS(so you can put each back spot on ,If required)Adjust each the SAME amount of turns (ie 5 or 6 turns each)These carbs are renown to spit more so on low revs..Becouse of the slow air flow...BUT its also a symptom of maybee 1 or 2 cylinders on weak mixture...So adjust each little screw the same amount of times as i said from the RIGHT IN possition...This should get you by till the tune up.....Kev.hope this helps..

[BIF]

Everything stated is correct with the addition of two additional and silly items, 1: ensure that you have not overtighten the "O" ring carriers, and that the thacharay washers are not tighten right up, ie either these or Webers need to "float" a little.

Barry