several years ago I split a Pontiac rochester 2bbl's shaft at the middle and added a linkage tab to the pass end of the pass. shaft, then ran a short rod back to a "jackshaft" arrangement located about 2" behind the carb. Both the carb and the jackshaft were mounted on a common alum plate which was drilled to mount on a four bbl clifford intake. The jackshaft was a way to arrange the primary one bbl (driver's side) to be continuously operational and let the pass. barrel to be brought in at approx 2/3 throttle at a rate that would make both wide open at the same time as in a progressive tri-power set up. Mods to the "secondary side would only be the elimination of that side's idle mixture screw (passage filled with lead) and additional spring to bring back secondary butterfly. I worked on it only long enough to prove the linkage would work-never ran it. Would only be feasible on large rochester,stromberg(mopars),or the big two bbl holleys, as the small roch. 2 bbls ran ok on even the stock 194's.
I originally thought of trying to somehow index the shaft, to bring in secondary- but could not figureout how to make both be at wide open at same time. My method worked, but needed to be condensed in size. Gave up interest
