Dual 40 IDF'S really weird . . . ., defective Spanish casting???? Options

[ghettojet]

1.8 engine rebuilt by me.New Weber IDF's from CB Performance.
Engine is being bench run
Fuel pressure 3.0lb,even tried a little less at one point.
Good strong spark all around
Timing is on.
No gas in idle circuit cylinders #1 & 4
Mixture screws on this carb have no effect
took apart carb,blew air through idle jet passages
double checked float height.
all good.
Compression good
engine has a few hours on it
Finally I swapped carbs
Problem follows the carb
Now #2 & 3 not "participating"

air correction 2.00
emulsion tubeF-11
Main 1.15
Idle .50
Venturi 28mm

Only thing I can think here is that the actual casting is defective internally?
Seems far fetched
Am I missing something?
not sure what I can do except return carb to CB Performance
Would rather not do this
Please advise

[Superhawk996]

This is a confusing post to me . . . But maybe I’m not reading it right. Cylinders #1 and #4 are on opposite cylinder banks.

Do you have problems with one carb or both?

Have you verified all air bypass screws are closed? An air bypass that is too far open will completely negate the idle circuit for that barrel that has the air bypass open too far.

You say idle circuits aren’t getting gas - based on what? What are the symptoms? Sort of sounds like you’re implying the engine is only running on two cylinders? If so how did you verify that it is only running on two cylinders?

What has been done to balance airflow and synchronize the carbs? Are you trying to tune with all linkages connected?

Just not enough info to address your question