if you have a low vacuum engine you need a weak power piston spring, or it can hold the metering rods open, causing poor running due to a rich mixture, or so i have read.
(that is why at one time i stated that a vacuum leak could cause a rich mixture, and was severely thrashed. i usually stay out of carb talk, but i saw the two question marks and thought i might speak)
i usually stay out of carb talk, but i saw the two question marks and thought i might speak)
