I'm not sure if I understand. If they are working properly, you should not feel any openning at all. They should just move. The spring resists the vaccum caused by airflo. So as the secondaries open, if the vaccum present drops (like the sec are openning before the engine is really ready for them) then the secondaries will be forced closed by the spring. Thsi happens immediately, so you would never notice it. So some questions..Did you change springs already? If so, was the small check ball in teh secondary vaccum pod re-installed (it must be, dont run without it)? If you did, what color is in there now? Witht he small cubes, I would think the 600 needs a very heavy spring to operate properly because of the limited airflow the carb primaries see. (basically, the secondaries may not open fully at all on a 273 unless it really revving)
