The choke on my 440-SIXPACK setup isn't working right. The rod seems to have a rough spot and the plate on top won't close all the way to let the car start right and won't open up all the way to let it run right when it warms up. Lots of black smoke. Anybody else had this problem???

 

Sounds like worn out or damaged thermostatic spring, when these things start to fail the spring will try to set at a different angle and the link will then start binding on the cover.