Flat spot accelerating in my Euro GT4

idle hangs at 2k when sitting and blipping throttle right?

1ST and most important-are the cams timed according to inntake valve closing and exhaust vavle opening, combined with a minimal lobe center deviation(adjustment is not very fine on these cars, as compression is so lo its just not THAT important), but centers and relationships are...as well as leading bank and trailing bank...???

..did you use a mercury column and a 5 gas analyser with c/o port acccess to tune this thing?
if not/are unable to, due to lack of equipment, you probably can't get it out...

do NOT make the common mistake of screwing with carbs first...95% of ALL carb problems are: event horizon problems(cam/valve timing), ignition mal adjustments, wires and plugs, adjustments to the basics, sick motor(LEAK DOWN)...dont look at the carbs first-excepting a clogged idle jet, obviously leaking acc pump diaphragm, or bad needle and seat, these webers just dont get screweed up that much....running problems will be elsewhere.

In truth, when new, in the hands of skilled clinicians, with all the equipment required, these era of cars were difficult at best to "do what they were designeed to do..."

 

Advance the static timing, put in the old idle jets, lower the idle speed, and crack the idle mixture screw on the Left rear carb 1/4 turn richer than the others.

recurving the distributor will be even better.

I successfully run 12 BTDC at idle, and 32 all in, and it makes a big difference.

 

From my experience , in large part due to the lower quality fuel available today, we have to run at least .060 idles.

 

"We" means you and I subsidizing Iowa farmers by filling our tanks with corn.

I believe the Original Post is from a land of good gasoline, where they speak of "Dizzies", Carbies", and "over run", and corn is for eating and not for securing votes in a swing state.

 

popping on overrun means its too lean (lean misfire). back the idle screws out to 3 turns, and see what happens, i bet the popping goes away.

Most guys run 60 idles, backed out 3 turns, which provide enough fuel to eliminate the flat spot around 3k rpm as you transition into the mains, and also provide more fuel when you snap the throttle plates shut at high rpm to eliminate the lean misfire.

 

popping on overrun = too lean on the idle circuit
hard time transitioning through 2-4k rpm range also means too lean on the idle circuit