[horvath]

I just got my truck back from a total body restoration ... it sat for 3 years and I had all kinds of issues to deal with before I could get it back on the road again, but back on the road it is! Halleluyah!

I had the idle working nicely, but I wasn't yet sure about the setting on my electric choke. I took it through inspection the other day and, on my way home, while coming to a stop, it suddenly stalled out on me. I didn't know what was going on until today, when I realized it was nothing but my idle setting.

Problem is, right now I have it idling at 1200 rpm and when I put it in gear, it drops all the way down to like 500-600 rpm ... I'm thinking it's probably the electric choke setting because that affects idle, too, right?

I've got a Chevy 350 w/headers and a mild cam and a 350 Turbo automatic trans.

Before, when it was just in the garage, I had it idling at 1100 rpm and when I put it in gear it would come down to 700 rpm. This was working fine ... but once I got it out on the street and in the cold (32 degrees) weather, I'm not getting the proper idle.

Can anyone steer me in the direction I need to go to set up my electric choke? Or do you have any other suggestions about what the problem might be?

Thanks!

Alan

[DanielC]

Step one, get the ignition timing right.

That is too much of a RPM drop. Your idle mixture is probably a little off.

Get a vacuum gauge, and use that to set the idle mixture. You will have to do this with a warm engine. Make sure you run the exhaust outside. If your idle mixture is rich, it is also making a lot of CO (carbon monoxide, the bad stuff that will kill you).

Try to get the highest vacuum at an idle, with the idle speed where you want it. You will have to go back and forth between the idle mixture screws, and idle speed, repeatedly.

Once you have the idle mixture, and speed set correctly, and you have good throttle response, then you can play with the choke settings. The choke should only be used when starting the engine, when it is cold.

I have an electric choke on a FE390 in a 1974 Ford pickup. I rarely drive the truck, and my quick and dirty way to use the choke is this. It is hardwired, with a fuse, direct to the battery.
I start the truck, and after it has warmed up a little, I go and plug in the fuse, and let the choke heat up, and open. The rest of the day, if I am using the truck, I just leave the choke hooked up, or heated, or opened. At the end of the day, or when I am through using the truck, I then unplug the choke heater fuse.

[horvath]

Great help. Thanks, Dan!

Alan

[lanier ledford]

On all adjustable chokes I pick a morning that about the average for my climate in the winter and loosen the screws around the choke until I can turn it. I hold the throttle open a little and turn the choke outer housing until it just closes the choke and lock it down. That way when I touch the throttle it'll close the choke. As the engine warms up the choke will open. If it opens to soon, just close it a little tighter. You might check it in the summer again to improve gas mileage. You do have the choke hooked to a power suppy don't you?

[horvath]

Originally Posted by lanier ledford

On all adjustable chokes I pick a morning that about the average for my climate in the winter and loosen the screws around the choke until I can turn it. I hold the throttle open a little and turn the choke outer housing until it just closes the choke and lock it down. That way when I touch the throttle it'll close the choke. As the engine warms up the choke will open. If it opens to soon, just close it a little tighter. You might check it in the summer again to improve gas mileage. You do have the choke hooked to a power suppy don't you?

Thanks, Lanier.

Yes, my choke is on it's own power line.

I didn't know about holding the throttle open a little ... it did bother me a bit that when I turned the choke housing till the choke closed, that I could then turn it the other way, about a quarter inch, before it started opening again -- I thought, "Where is the proper position for this!?"

I'll try your technique ... thanks.

Alan

[41'srfun]

If you will go to the Edelbrock site they have an online manual that you can download as a pdf file that gives a good description of how to set the electric choke on the 1406. It also has a tuning guide and a good description of how the carb works and how to tune it. I tried to copy and paste the link, but couldn't get it to work.
I have been experimenting with the carb on my 54' Chevy truck to try and improve the fuel mileage a little and also used it to help me set the choke and fast idle.

[horvath]

Originally Posted by 41'srfun

If you will go to the Edelbrock site they have an online manual that you can download as a pdf file that gives a good description of how to set the electric choke on the 1406. It also has a tuning guide and a good description of how the carb works and how to tune it. I tried to copy and paste the link, but couldn't get it to work.
I have been experimenting with the carb on my 54' Chevy truck to try and improve the fuel mileage a little and also used it to help me set the choke and fast idle.

Thanks!

Here's the link: Edelbrock Owner's Manual

[Alaska_Man]

Alan, I too, have a Edelbrock 1406 carb on my 350 Chevy engine w/ electric choke. First off you want your engine to idle around 700 to 900 RPM. The first problem I had, with mine, that I found out later, was that the fast idle screw was set to high and catching on the fast idle cam and not letting it drop down on the regular idle screw. It is right behind the regular idle screw, down and behind on another cam. Back that off to make sure that the throttle cam can come back to rest on the idle set screw. You can reset it later. Then set your choke setting. I tried several ways and found the best for me was to bring the engine up to temp., then hold the throttle open a little. Loosen the set screws on the choke. Then turn the adjusting cap until it closes the choke. Then back it off just until it fully opens. At that point I re-tighten the cap screws. It worked for me, hope it works for you.

[horvath]

Thanks, Alaska Man ... that's some very helpful info.

I'm gonna read the manual now ... then I'll probably understand your info even better ... and tomorrow I'm going to see if I can't get it tweaked up to pure sweetness.

Alan

[horvath]

I've taken notes from the Edelbrock manual about setting the Idle Speed and I have a question:

They say "Set speed to desired RPM with the Air Screw" ... the Air Screw!? what is that? They *must* be referring to the Idle Speed Screw, right? That's the only way I know of to adjust the RPM.

What is an "Air Screw?"


Alan

[matts37chev]

idle speed screw is the way i read it
you are right

[horvath]

Thanks, Matt. I can't wait to get up tomorrow and work some magic!

[Alaska_Man]

Originally Posted by horvath

I've taken notes from the Edelbrock manual about setting the Idle Speed and I have a question:

They say "Set speed to desired RPM with the Air Screw" ... the Air Screw!? what is that? They *must* be referring to the Idle Speed Screw, right? That's the only way I know of to adjust the RPM.

What is an "Air Screw?"


Alan

Well Alan, I'm not sure, as my manual for this carb is out in the shop. There are two steps in setting the idle speed. First set the idle at whatever RPM you want. Then, and this is what I think they are talking about, you have to adjust the idle "AIR/fuel" mixture screws. Turn them clockwise and they make the mixture more "Rich." More fuel than air. Turn them counter-clockwise and they "lean-out" the mixture. More air than fuel. There are two of them on the front of the carb at the base. As you adjust these, the RPM will go up or down. You to adjust these to the HIGH'est RPM. Then you have to reset the idle RPM, using the Idle adjusting screw, to the RPM you want. Don't remember which, air/fuel mixture screw you start with, but should be covered in the manual. Hope this helps. Bob

[horvath]

Thanks, Bob.

They refer to the Air/Fuels screws as "Idle Mixture Screws" ... so what they call the "Air Screw" (silly term!!) can only be the idle adjustment screw.

Anyway, I have a good understanding of it all now and I'm looking forward to doing the deal! But it's been snowing here all day, so I'll be doing the deed tomorrow (Sunday).

I sure do appreciate HotRodders.com and all the help I always get here!!

Alan

[75gmck25]

If the engine dies out at idle under load, there is something wrong with the idle mixture. You might get around the mixture problem by setting a faster idle, but idle should not need to be any higher than about 900 rpm in Park unless you have a very aggressive cam. With 900 rpm in Park it should then drop to about 600 rpm when you put it in gear.

I also suggest you slowly turn each mixture screw in while idling (counting the turns is a good idea) until the engine stalls out. If that does not work (engine keeps going), you have a vacuum leak that is affecting the mixture. Once you verify there is no leak, then use the Edelbrock procedure to set the idle mixture and then the idle speed.

You can also use a mirror (at an angle) and a flashlight to look down the carb when the engine is idling. If you see any raw fuel dribbling on either side, the air venturi may be blocked with debris and making the mixture too rich.

My electric choke works fine for cold starts, but runs too rich for a hot start after a short shut-down. I assume the choke goes back to a rich setting after shutdown and it takes while to open the choke again.

Bruce