Carb throat popping at speed, New Problem!!! Options

[LetoAtreides]

Ok, so I know I've posted this before, but I still cant figure it out, and I need to know all of the possible circumstances under which this condition occurs.

One of the throads on my dual carbs is excessively lout at speed. It sounds like pop-pop-pop.

Any ideas?

[LetoAtreides]

Ok, so I timed my car by the book, and it idles a lot smoother now. However, I'm getting more backfires out of the carb throats upon revving than I was before. So. I adjusted the valves (again) and re-timed it to no avail. There were no stuck valves or pushrods. I also ran a compression check and got 140 across the board.

There is a strange whistle when I shut of the car, right when the engine stops running, though.

Any ideas?

[ArtechnikA]

Ok, so I timed my car by the book, and it idles a lot smoother now. However, I'm getting more backfires out of the carb throats upon revving than I was before.

There is a strange whistle when I shut of the car, right when the engine stops running, though.

But we're getting someplace.

So what are these carbs?

manufacturer,
throat size,
venturii size,
main jet size,
idle jet size

What color are your plugs ?

Does the exhaust smell stinky-rich with smoke?