Carb Basics question, high idle

[bil1024]

Here is what I have:

Ford 302 from 89 Mustang. Installed 4160 Holley Electric choke with electric fuel pump. Pressure gauge reads 5psi. Now no issue starting. Idles at 900 after warm up goes to 1900 RPM. Choke adjusted to max, fell that is to high. I have adjusted the float as per Holley video but the idle is really high. No vacuum leaks. Any suggestions ?

[NAZ]

Sounds like the fast idle cam is not moving to the warm idle position (note, the cam will not release from fast idle even when the electric choke commands until you move the throttle once). You state you have the choke set to max; have you tried setting it to minimum? Also, forgive me if this is too basic but there are two idle screws -- one that engages the choke fast idle cam to control the fast idle speed and one for the warm idle when the choke is in the off position. The fast idle screw is located on the passenger side behind the circular housing that holds the bimetallic spring for the electric choke.

[bil1024]

Well when I pump once the cam releases and the chole closes, I have the idle screw out on the drivers side so it does nothing right now. The passenger side I am adjusting a bit at a time. The choke opens a bit but idle goes high after 5 minutes. When in gear, the rpm is lower, say 1500. Any suggestions appreciated

[NAZ]

Hard to troubleshoot over the internet but start with the basics. Ensure you have no vacuum leaks. Some of the usual suspects are intake manifold gaskets, carb gasket, vacuum hoses, pcv valve. If not sure how to check for leaks you will probably find a YouTube video demonstrating the procedure.

Ensure that there is nothing holding the secondaries partially open at idle and that the throttle cable or linkage is allowing the throttle to close fully (contact with the main idle adjustment screw).

Adjust the electric choke bimetallic spring to full minimum and ensure that the choke is being commanded to open fully after several minutes. You don't have to start the engine to check this just turn on the ignition to the run position and the electric choke heating element will heat the bimetallic spring. If not make sure the heating element is actually working and if so, ensure that the fast idle linkage is not binding.

If the electric choke is functioning properly then while the fast idle cam is engaged (engine cold) adjust the fast idle screw to a more reasonable RPM.

[Railroad]

Sounds like you have the fast idle cam screw run in too much. With the choke in max open position and the fast idle cam dropped to the low idle step, back the screw up until it does not touch the cam.
By your statement, you will probably need to run the idle speed screw, drivers side in until it moves the throttle.
Another issue that might be occurring, you are not keeping constant current to the electric choke after startup. If this happens the auto choke will come back on and pull the fast idle cam back up.
If you are not following a Holley adjustment guide, with the throttle held wide open, turn the auto choke housing until the choke blade is about 1/4 inch from full closure. If this does not get the job done or is too rich, adjust the choke housing accordingly, leave the screw alone.

[CraigS]

To clarify terms look here
http://documents.holley.com/199r11081.pdf
Scroll down to figure #8. This is how the choke idle speed is adjusted.
Scroll down to figure #14. This is the most often used idle speed adjuster. It adjusts the throttle plate in the primary side only. Since the secondaries are vac operated holley doesn't even mention adjusting them.
To add to what Railroad said about power to the choke, it must have a full 12 V all the time the key is on. Also, although it may be convenient, do NOT get that power from the coil or any ignition components. Run a separate power lead from a key on source in the fuse box.

[awd-turbo]

isnt there a tan wire for the electric choke on the ron francis harness? Cant he use that craigs? or is that no good?

[scottiec]

isnt there a tan wire for the electric choke on the ron francis harness? Cant he use that craigs? or is that no good?

That wire is fine to use for the electric choke.

[bil1024]

Hey thanks everyone, seems better now that I backed off the fast idle screw and used the idle screw to adjust the rpm at idle. I have the choke set to the last tick mark, which also seems fine for now. My only question is, the fast idle cam seemed to be stuck upwards a bit after running awhile, the RPM were creeping up so I knocked it down by hand and it leveled out. Granted, it did kick down when I pumped the pedal , almost like to was hung up on something ?

[NAZ]

If it continues to give you trouble don't be afraid to pull the carb and give the electric choke system a good look to ensure nothing is binding. It's really a simple system and it's not like you're going to break something. And you may become a bit more familiar with how it works in the process.

[Railroad]

Holding the throttle wide open and the choke open by the cap adjusted to max lean, move the high idle cam up and down to make sure it is free. The fast idle screw may still be too close to the cam. Make sure it does not drag with the cam in the down position. It does not have to be close to the cam in the off choke position, about 2 or 3 business card thickness clearance. I have seen the wt get broken off the bottom of the plastic fast idle cam. Make sure it is still intact.
You can check the engagement of the bi metal spring in the choke cap, by holding the throttle open, with the choke cap loose, turn it both directions. The choke blade should respond in BOTH directions.

[CraigS]

That wire is fine to use for the electric choke.

That is fine. I just wanted to assure he has it correct. I haven't worked much w/ the current harness, and wasn't sure of wire colors, so provided some backround info just in case.