I have been tinkering with my carbs (dual Weber 44 idf) for a while. I have my fresh rebuilt running very well however I am having an issue that I was hoping everyone could help me with.

If I slowly accelerate from a stop, my A/F ratio gets quite lean (17:1) from 2000-2500. Otherwise the a/f ratios are fine (13:1-14.5:1)

I have tried various idle and main jet adjustments and if may slightly improve things however not much and then I mess up the idle or main circuit then.

Here is my setup:
Dual Weber IDF's
Idle jets- 55
Mains-155
AC- 190
ET- F11
Venturis- 36mm

engine- 4 cyl 2258cc

Mallory distributor set at 30 degrees (have tried various different settings and no change in the problem)

Everything is synced well. Fuel pressure normal. The carbs are a fresh rebuilt

personally I believe that your venturis are far to large.
I would suggest you go down to 32 vents and tune from there.
It should help with the transition.

Also, the f7 emulsion tubes may help.

Rich

I had 36s on my 2056 and had a similar problem. 32s are the way to go.

36s are too big for even your displacement at the RPMs you're using it for. Simply not enough "suck" (velocity) through the throttle bodies at that RPM to make the carburetor do it's job efficiently with such large chokes. If you ran it wide open all the time they would probably be about right.

I haven't seen 44s with adjustable accelerator pump levers before, but if you have them, you could try turning the nut in a few turns to engage the pump a tad earlier. Doubt this would carry you through the low RPMs and into the transition though.

I have seen this if the car is idling on the progression circuits: idle speed screw is turned too far in. Then the progression holes aren't able enrich the mixture for light throttle application or transition off-idle.

Make sure the syncrometer is measuring 3-->3.5 at idle. If it is above, you are likely already on the progression circuit.

Sounds like the typical lean transition issues.

You could do one of two things:

1 - Go with F7 ET's and increase idle jet size. That will enrichen the mixture from your progression ports and slightly decrease the velocity when you come onto the main jets. You may also need to reduce main jet size slightly due to the F7 being an all around richer tube.


2 - Reduce your vent size, decrease main jet size and possibly increase idle jet size. That will put you on the mains sooner and enrichen the progression port mixture (with idle jet change). You will also need to reduce main jet size due to increase vacuum signal to mains.

Either way your spending money. Both will help but I can't tell you which one will work the best for your particular application.