Just acquired an 83 with the 12a and a racing beat holley setup. I am curious as to the layout for the carb...if there are any manuals anywhere online that is, and more importantly where the idle mixture screw(s) are located. Idle speed was easy to find

 

google "Holley 4160 schematic" and it should yield plenty of diagrams of varying detail.

as for the idle mixture screw, look on the float bowls. there should be a small screw on each (there may be 2, but you want the smaller, lower one). those are for idle mixture.

 

When you say lower, you mean lower as in elevation or towards the rear of the car?

 

The idle mix screw on a 4160 is on the primary side with the metering block..theres only one.

Buy a holley carb book and read it front to back. Then youll know how to tune it completely. Check Amazon for a used one.

 

actually I hav a rb 4160 holley and it has 2 idle screws on the primary side, one on the front toward the rad and one toward the firewall

 

Yup, primary block should have 2 on opposite ends.

 

Nvm I dont remember im not sure what im saying

 

Likely doesn't have center hung float bowls, but this is the jist.

 

Whatever you do to one mixture screw, do the same to the other side. They each need to be the same amount of turns out.

 

I get my 12a street port holley kit from RB on Tue. I'll posy some pics after I install it, so you can compare.

Edit: Nevermind, this wont help you at all.

 

Good point