I have an 89 RS lo3 carbed motor with a holley 600 vac sec. I've noticed that once the car has warmed up that it hesitates only at a stop though, like at a stop light. I haven't tried messing around with the idle mixture needles yet , as i've tried to work my way around to hopefully find that the answer is something else. The fuel pressure is set at 5.5 pounds, and I've also noticed that when I raise the fuel pressure up to the max of 7 pounds it does go away but then it's way to rich.

 

I bet its only really noticeable when accelerating off-idle right? Check your accelerator pump linkage. It should have no slack in it... if it does, thats your problem - its momentarily leaning out and bogging down when you open the throttle with no pump shot to compensate for the increased airflow.

 

Never when I am accelerating just at a stop, but when I start it up it starts fine but when I give it gas it has to clear it's throat so to speak. It's Only in lower rpm but then clears up after a few seconds. If I start it after it has been drivin for a while I have to hold the throttle down for a few seconds. If I'm just cruising it acts perfect and under hard acceleration it's awesome. I did fail to mention that I have a 10" converter that gives me with my setup, a 2500 stall. Not sure if that would have anything to do with it? The carb is brand new as well

 

Thats exactly what I meant, although I could have worded it better. My bad. Check your accelerator pump linkage - 99% sure you'll find the problem there. Check the pump cam position too... at rest (idle) the accelerator pump arm should look like its sitting almost on the 'peak' of the cam, not flat along the side.

 

What's the best way to go about adjusting the linkage

 

The only way to adjust it is with the screw/nut/spring on the end that touches the accelerator pump lever. Hold the nut with a wrench and turn the screw 'out' to remove slack, turn it in to open a bigger gap. There should be no slack in the linkage, but it shouldn't feel 'tight' if you try to jiggle it around side to side. Just adjust it enough to take up any slack in the linkage, maybe just a little might tighter, and it should be ok.

 

OK great that's what I did a little while ago, so on the way to work tomorrow i'll see how she acts. Thanks for the feedback though.