brianj5600
Active Member
to clarify, right now, the way it is set up, the primary idle speed adjustment is backed out, such that it does not raise the idle speed. I turned the secondary idle speed screw in to raise the idle speed to my liking (850 rpm in neutral).
BrianJ, you wrote:"Air coming through the cracked secondaries is not pulling fuel." The holley 4160 I have does meter fuel in the idle side of the secondaries. I don't see how this is contributing to the problem when my idle mixture screws work fine and my idle a/f is good (12:1)
The first thing I would do is get the primary blades where they need to be. Look at this picture and set the primary idle screw so the the T slots look like this http://www.competitionplus.com/07_15_2004/photos/carb_rebuild_07.jpg Then put it on the car and use the secondaries to set idle. Do not adjust the primary idle screw.
What I was saying is that with the primary idle blades completely closed too much air is going through the secondaries. All this air is like a vacuum leak since it does not cause the carb to flow fuel. The first part of moving the throttle does not start flowing fuel from the transfer slot and the carb can not catch up flowing fuel until the mains start flowing. Setting the primary blades like the picture will make the transfer circuit start to flow fuel as soon as the throttle is moved off the idle screw. The way you have described, the throttle moves from the set point to the point in the pic and no additional fuel is added. Once it is at the throttle position in the pic it starts adding fuel, but by then it is lean and can't catch up. Sorry for the ramble.