Idle Idle Idle

[1965-Mustang]

I am having an idle with my car. I have figured out now that after WOT the car will idle at 2000 rpm. When I shut the car down and restart it goes back to 800-900 rpm. While driving normal it sometimes will start idleing at 1000-1300 rpm though. But mostly after a drive without hitting WOT it will stay at 800-900 rpm. Since it goes back to normal after I restart the car I am thinking this problem is not mechanical; nothing seems to be binding or hanging in throttle linkage. I thought it was a vacuum leak at first but wouldnt it idle like this all the time? What could this be? Ignition? I have messed with the carburetor more times then I care to. It is a Speed Demon and I have played around with every setting. I tried messing with the 'Idle-Eze' screw but I am not sure how/what it does. I am at a loss, any help would be very appreciated as it is extremely annoying with a 2000 rpm idle.
Thanks.

 

[JB66]

Be nice if we knew the engine/carb/trans combo.

 

[10secgoal]

Does sound mechanical. When it does this, have you tried to lift the pedal to see if the idle lowers ? Or you can try to partially disassemble to distributor and hit it with soem carb spray on the weights and springs. Maybe it's getting gumbed up and not letting the timing return to normal.

 

[2nd Mustang]

I have the same thing happening on my 600 Holley. This is a new Holley, but same thing happened on my old one. Installed new intake gaskets, same thing. Made sure linkage and gas pedal weren't hanging up somewhere. Installed double return springs, same thing. I just blip the gas pedal when coming to a stop and it usually drops the idle speed, but sometimes not until I try a few times. The only other thing I can think of is maybe the motor mounts are bad and causing the motor to bind. The linkage is such a simple design, I know the answer is going to be a simple one.

 

[red65]

Not the same carb, but could be the same problem -- the secondaries on my Holley 4-barrel on my old '85 5.0 used to stick just a bit open, resulting in a very high idle (around 2k). Solution was simple - disassemble, clean off the gunk, lubricate and reassemble. Works like a charm. Easy enough to diagnose, too.

 

[1965-Mustang]

I have the same thing happening on my 600 Holley. This is a new Holley, but same thing happened on my old one. Installed new intake gaskets, same thing. Made sure linkage and gas pedal weren't hanging up somewhere. Installed double return springs, same thing. I just blip the gas pedal when coming to a stop and it usually drops the idle speed, but sometimes not until I try a few times. The only other thing I can think of is maybe the motor mounts are bad and causing the motor to bind. The linkage is such a simple design, I know the answer is going to be a simple one.

This is exactly my problem...I aslo changed the intake gaskets, pulled up on the pedal to see if was caught, I have the return springs. And the blip of gas works for me sometimes too, sometimes not; just like you said. I have also taken the carb off and sprayed down with carb cleaner, not really thoroughly though. I will try the cleaning of the distributor and some more looking at the secondaries. Thanks so much!