[NateB68]

Hi,
I have a '68 cougar (302 2bbl) and when I start is cold it runs pretty good for the first minute or two. Then it starts to bog down on high idle, and eventually it will stall on high idle, but if you go and take it out of high idle, you need your foot slightly on the gas or it will stall right out. Need some help please.

Thanks,
Nate

 

[Bad69cat]

You may just need to increase the low idle speed - but check that your choke is working properly first. Sounds like it is since it starts cold (i.e closed or just about), as it warms the choke should open gradually, when you push the pedal if the choke is warnmed it should also allow the low idle screw to rest on the cam - you should adjust this to about about 700-800 RPM. If it still doesn't stay running you may need to check for vacuum leaks around hoses/carb base/etc....

 

[mmmeat]

Hi,
I have a '68 cougar (302 2bbl) and when I start is cold it runs pretty good for the first minute or two. Then it starts to bog down on high idle, and eventually it will stall on high idle, but if you go and take it out of high idle, you need your foot slightly on the gas or it will stall right out. Need some help please.

Thanks,
Nate

Nate-

I think this is pretty darned common in a carburated Fuel system, frankly. I have the exact same issue with two FE motors and it is just usually a matter of getting things warmed up. Warm weather would probably be helpful (and I hope Arizona warmth and dryness will help, gulp!) and a choke and carb is only "set up" with the two or three idle speeds at the temp at which you first set it. I just nurse it along and am ready to goose the throttle a little to avoid that fuel starvation right as you're describing..I did it as a kid in our old Fords and it's still often a necessity. Faster "slow idle" helps, but then you have a fast idle to deal with..Don't be alarmed at constant tinkering and idle speed and timing advance adjustments..it's a part of life with a Carburated system with Points and condensers and changing temps and humidity levels..

This is all why fuel injection is so nice

 

[Seafoam jcode]

I have the same problem happen on both my '68 302 4V and my '85 5.0L 4V when the temp is between 32-40 degrees and it's raining or just really humid out. Both electric chokes are working fine, both engines go to high idle right when you crank them up, run smooth as silk and then after a few minutes the idle quality will start to degrade slowly until the engine is coughing and sputtering. The choke on each vehicle closes down to the proper gap and then will slowly start to open up after a few minutes.
This only seems to happen when it's humid or raining out and between the temps noted. If it's cold and dry, the choke will come of and the engine will still run smoothly. I still have the fully functioning factory '85 aircleaner with the dual snorkels and dual carb heat tubes down to the LH and RH headers on the '85 Mustang and this still happens in humid conditions. Some believe this condition is due to carburetor ice forming in the throat of the carb when it's humid. What really sucks is that I can drive it for nearly 20 minutes with the choke completely open and the coolant at normal temp and it will still run rough as if the plugs are fouled. My solution that seems to work every time: Start the car up and wait for the idle quality to degrade. Shut the motor off for about 5 minutes and let it heat soak while you go inside to fix a cup of coffee. Come back out, start the car and be on your way.

 

[Bad69cat]

Or ditch the electric choke an go manual.....I found this to be very helpful with finnicky ones. Mine is manual and like you guys say, it depends on the day and the cat's mood. If it starts to get rough, a little tweak on the choke setting smooths it right out. It's amazing how little it takes sometimes to act up.