1/64" Holes in primaries - done it?
 

Has anyone every tried the 1/64" in the primaries so they can stay shut, as opposed to moving the set screw on the secondaries to get more air in. Hopefully to utilize the idle circuit?

I have and it works if it is needed. The way to check is to set the idle as close as you can and pull the carb and see how much of the idle transfer slot is exposed under the butterflies. If there is more than about .040" there will be little to no response when the idle mixture screws are turned and excess fuel will be dumping through the slot. Drill the holes and try it again. If need be drill them larger and if your carb has 4 corner idling you can also drill the secondaries. Don't go to far or you will have to get some new butterflies. I have had good resluts with this type of idle tuning. Ideally the idle mixture screws will be 1 to 11/2 turns out for proper and the motor should stumble when they are turned in and from there they should be backed off 1/2 turn.
Carbs are fun. Good luck!!

The Nickerson carb I just installed has 4 corner idle screws and has 1/16th holes in each of the 4 butterflys. Idles perfect!

Eric

I have the holes in my Holley 780's. I dont remember the size but it was the only way I could get the idle mixture screws to do anything. It worked great for me.

Kaamacat,

I have drilled 1/16 holes in my throttle blades. I had some idle problems because of the drastic drop in RPM from Neutral to In gear. It appear that those Kaamas really pull the RPM down. Before the holes, in order to get the idle high enough in gear ( about 700 RPM) I had to get about 1100RPM out of gear. To get this RPM i had to turn the idle screw so high that it started to come off of the idle circuit. Drilled the holes, and it worked perfect. good idle in and out of gear and throttle blades well with in the idle transfer slot.