Dual AVS Carbs, Off-Idle Flat spot

[74Dusted]

Anybody ever encountered this before?

I have a pair of 750 AVS carbs on top of my 6-71 Blown '73 340 Duster, with Progressive Linkage.

If I ease into the throttle, there's a 1 Second Flat Spot right off idle where nothing happens. 1 Second later, WHAM, I'm hanging on for dear life. If I hammer the throttle, there's no flat spot (just a burning rubber smell... and lots of tire squealing)

Both Accelerator Pumps are functioning properly, no delay at the squirters. It almost feels like a delay in fuel, even though both Accelerators are working.


The AVS carbs aren't permanent, but I'd like to fix this issue, until I get around to replacing the AVS carbs with a pair of Thermoquads.

 

[moe7404]

this is the common lean ldle circuit. on the primary venturi cluster there is two brass tubes. the small one is the idle tube. the small part is the idle jet. its inside dia may be from .032 to .035 inch. get a set of small drills, and a pin vise. use the drills to find the dia of the jet. incress the dia by .001 to .002 to start. hold it with the tube facing down, so the chips fall a way from the tube. and drill by hand. a little is a LOT. if you go to far. you can solder it and redrill. but it is not easy. that lean idle started in 1968. most AFBs dont have the trouble. but AVSs do..