yes, Ive heard of adjustable pulloff for certain carb numbers. I guess you would have to call about that one. I have never seen one that has the adjustment for the rate of opening. Another option would be to drill your diaphragm out totally and then just use a "pill" in the vacuum line feeding the pull-off. (you could use a small piece of plastic drilled to various sizes. and installed in the line for the restriction) then you just keep 3 or 4 of them (at different size drillings) on hand and you just swap out the vac. line for the adjustment. I read that in Cliff's book. Seems like a great idea.