At anything from just a couple minutes after start up to just about 180 on the water temp gauge the idle is smooth or as smooth as it can be given the cam with a very consistent idle. When the temp gets to normal operating the idle rpm in gear will get a little erratic almost to the point of it feeling like it drops a cylinder and picks back up and then feels like a miss again, and on and on. In gear idle is around 800 and in park it will smooth out slightly at around 1000 to 1100. The best vacuum reading I get is 10 with an initial timing setting of 20. I thought the problem with the old Edelbrock carb was it not getting a decent vacuum signal causing the metering rods to bounce up and down and the carb to hunt between the idle and main circuit. This new carb made things overall slightly better.