new carb issue on old carb...
 

So I recently rebuilt my holley 4160 vac. secondary carb. Everything was good until recently the motor won't idle correctly. It surges real bad and won't hold an idle. So I checked for vacuum leaks with starter fluid, and that all checked out ok. I then tried to adjust the idle mixture screws. They are not working, and when I screwed them all the way in(closed), nothing happened there either. I suspect a bad power valve, but not sure. Isn't the motor supposed to die when I screw the air mixture screws all the way in? For the life of me I can't figure out why my idle circuit isn't functioning at all. I checked to make sure the butterflies were in the correct position, so as not to be past the transition slot, so what gives?? I also checked the float level and it is good too(just a small trickle when sight plugs are removed) Any ideas?

Re: new carb issue on old carb...
 

Are you sure you have the transition slot covered. Hook your vac pot on the dizzy to manifold vacuum then turn down your idle and see if the mix screws start working.
You might also need to open the secondaries a touch so you can close the primaries more. Try the vac pot first.

Re: new carb issue on old carb...
 

I'll start there and see...thanks for your help

Re: new carb issue on old carb...
 

I figured it out-turns out I had a blockage in my primary metering block. Purrs like a kitten again!!

:D