Weber 44 idf flat spot Options

[tornik550]

So I recently purchased new weber 44 idf's. They didn't work out well so I went back to an old set of weber 44 idf's that I had. I thoroughly cleaned the carbs, sprayed carb cleaner through all jets, tubes, etc. I have also balanced the linkage. Set the floats, etc.

The car starts well. Idle's well. When I drive the car I get a major flat spot between 1500 and 3000 rpm's. Below and above the car accelerates normally.

What changes should I make?

My current setup for my 2258 (dual webers, big cam)
-idle 55
-main 160
-et F11
-ac 200
-vents 36

Are there other issues that can cause this type of problem (timing,etc?)

[ThePaintedMan]

I thought I read somewhere that smaller vents give you more low end torque?

Potentially, and with a possible loss in high RPM power. It all depends on what the intention for the engine/car is. If it's to spend most of it's time at high RPMs, larger vents (within the appropriate range for the engine displacement and breathing ability) are the way to go. Read Tomlinson's Weber book. He has a copy of the Weber venturi selection graph that clarifies this. For a street car, smaller vents are preferable to increase velocity flowing past the carb circuits, which helps draw the appropriate amount of fuel from them.

In theory, every form of the Type IV below about 2056 (especially with Jake/Len's high flowing heads) intended for the street should be running 28 mm venturis.