Too many carbs, and/or carbs that are WAY too big for the application. You've got low manifold vacuum, venturi velocity too low, and a lean backfire on acceleration. Congratulations on reinventing the wheel- - - -your results have been shared by untold thousands of stovebolt owners who don't accept that the laws of physics are not "suggestions"!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!