Ford Muscle Cars Tech Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
186 Posts
Discussion Starter · #1 ·
I have reviewed most of the threads but have not found my answer. I am new to adjusting carbs. I wanted to tune in my carb now that I have added AC and things are finally running well. I just want to get to best mileage and performance. I turned all four mixture idle screws in and back them out until I got the highest vacuum reading (I think it read 15 or 16). I then adjusted the idle to 900 RPM without AC and 600 with AC running and in gear. I thought I had things looking good but when I turn it off it wants to turn over one more time. I know that the timing and everything was working fine until I started messing with it. Can someone explain what is causing the condition and what the mixture screws do when back in or out. I hate doing adjustment and not knowing what it is doing to the system. This is a SS-680-VS on a 351W.
 

·
Premium Member
Joined
·
1,330 Posts
Idle is to fast. How far did you turn the screws out? Do you have an A/R indicator? What is the timing set at? Are you using vacuum advance?
 

·
Registered
Joined
·
186 Posts
Discussion Starter · #3 ·
it is about 1 to 1.5 turns out done evenly. don't know what an A/R indicator is. All timing setting where done by the shop that built the engine. Don't know about the vacuum advance. Pretty new to tuning. All I know is it was running good before I added the compressor for AC then the idle was too low. So I decided to see if I could optimize the total performance of carb instead of just turning up the idle speed. I then read up on adjusting and called QFT and got just enough info to make me brave enough to try it myself. So basicly I know I created the problem I just not sure how everything works enough to adjust it to where it needs to be. At this point I feel like I am just adjusting in the dark.
 

·
Premium Member
Joined
·
1,330 Posts
To fast of an idle will cause run on. Idle it back down. You may need to get a idle stop solenoid to increase the idle when the AC is on.
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top