Ok first let me clarify that I am not a moterhead so this might be a dumb question. Is it possible to adjust your idle on a 305 with a TBI manually or does it have to be by the computer. Under the hood there is a label that says do not adjust idle it will adjust manually!!!!

 

There are a few tricks to fool the computer but you can only tinker with it by playing with your IAC and TPS. Does your cars idel not suite you? The stock tachs are notoriously off by the way.

 

you cannot adjust the idle, the computer is going to always try to find its commanded idle speed, if you start burning you own chips, you can change the commanded idle speeds. if you were to adjust it manualy to the point where you change the actualy speed, you are going to either be running the IAC full open, or full closed.

now, with that out of the way, to adjust the idle, you need to take a punch and open up access to the torx screw in the TBI that controls how far the throttle blades are open.

 

The location of the plug that is hiding the idel adjustment screw is on the front right hand side of the TBI unit (if you are standing in front of your car looking into the engine compartment) Its about 3/8" big, just take a punch to one side and pound it in the the opposite side of the circlular pulg, its a fairly thin plug so it easy to get out, and then clockwise turning the idle screw increased idle and counterclockwise decreases idle.

 

for instance my cars tach says its idling at 2000rpms, which is whooy- if it was going that fast it would be making more noise then it does.