Trying to get 900 idle

[profcucchi]

Hey guys, I've adjusted the carb rod from the top to get the idle at a consistent 900-1000. I can't seem to adjust the rod, or the accelerator cable any more. The carb rod has a slight curve to it, but should it be straightened?

I know it should be 850-900, so besides adjusting from the low end, what else could be done?

I'm thinking to just go at the idle screw (and the mixture screw, while I'm at it).

.

[bradartigue]

The rod is not the adjustment point. I'd leave the rod disconnected until you get the idle set.

Idle is always set with the mixture screw and the idle set screw. Once complete you reinstall the throttle control rod.

[profcucchi]

The rod is not the adjustment point. I'd leave the rod disconnected until you get the idle set.

Idle is always set with the mixture screw and the idle set screw. Once complete you reinstall the throttle control rod.

Thanks, Brad.

I have a local enthusiast on speed dial if I need the help. I'll read through your manual before turning the screws.



Im having trouble finding the idle screw. Is it in any of these pictures?

Also, in the middle picture there's a threaded sleeve. Should there be a screw here?

Thanks.

I know the carb is a Weber 34 ADF.

[bradartigue]

Nowhere in anything I've written do I say to adjust the rod. The rod is not part of the equation at all.

The idle speed stop screw is located under the choke assembly. If you look at this breakdown of an ADF:

http://www.artigue.com/fiatcontent/carbs/32_ADF.pdf

Look at the choke barrel, just below it.

The "threaded sleeve" is your mixture screw - it should have an adjustment screw set inside of it. If not then you need one or the carb will simply have a big old air and fuel leak right there - and you'll never get it right. Look inside of it. It is a primary point of adjustment.

In your picture to the right it looks like you screwed the choke setting screw all the way in. You'll likely get a very high idle when the engine is cold if left in that position.

[aevansgatech]

By my untrained eye, it looks like you're missing the idle mixture screw as well as a vacuum line to the carb. Idle mixture screw on mine is directly below the rubber line and idle speed screw is on the "right" side nearest the firewall.

Hope this pic helps! It's a bit dark

[profcucchi]

Nowhere in anything I've written do I say to adjust the rod. The rod is not part of the equation at all.

The idle speed stop screw is located under the choke assembly. If you look at this breakdown of an ADF:

http://www.artigue.com/fiatcontent/carbs/32_ADF.pdf

Look at the choke barrel, just below it.

The "threaded sleeve" is your mixture screw - it should have an adjustment screw set inside of it. If not then you need one or the carb will simply have a big old air and fuel leak right there - and you'll never get it right. Look inside of it. It is a primary point of adjustment.

In your picture to the right it looks like you screwed the choke setting screw all the way in. You'll likely get a very high idle when the engine is cold if left in that position.

Brad, I adjusted the rod because after pushing the accelerator, it would stick and rev high. By tightening it, I hoped it would help with the idle. Having read through your files, I returned everything to pre-tampering, and will adjust the screw, following your method.

Aevansgatech, I'll look later tonight. I'm hoping I'm not missing anything, but I have access to a parts car...

Thanks, guys!

[profcucchi]

Nowhere in anything I've written do I say to adjust the rod. The rod is not part of the equation at all.

The idle speed stop screw is located under the choke assembly. If you look at this breakdown of an ADF:

http://www.artigue.com/fiatcontent/carbs/32_ADF.pdf

Look at the choke barrel, just below it.

The "threaded sleeve" is your mixture screw - it should have an adjustment screw set inside of it. If not then you need one or the carb will simply have a big old air and fuel leak right there - and you'll never get it right. Look inside of it. It is a primary point of adjustment.

In your picture to the right it looks like you screwed the choke setting screw all the way in. You'll likely get a very high idle when the engine is cold if left in that position.

I have to laugh! I read through the Italian part of the pdf before seeing the English!

Bilingualism has its benefits.

[profcucchi]

Ok fellas, here's what I have, or don't...



Am I missing an outer part? It doesn't look like any of the pictures.

Also, how do I know when I've made or not made contact with the throttle stop lever?

Thanks, I'm really testing the limits of my car know how here.

[bradartigue]

You are fine with regards to the screws being in the right place.

The one in the center of your picture, the inset screw, that is your mixture screw.

Above the mixture screw is the base of the carburetor body. It has bolts holding it down, left and right. Just to the right of the right-side bolt is the idle speed adjustment screw. You can just see it hiding in your picture, in the shadows in the right side.

You need to:

Slowly screw the mixture screw in until it stops - don't go further and don't force it - then back it out two full turns.
Slowly screw the idle speed screw in until it makes contact with the throttle lever. You'll know it makes contact because the throttle assembly will start to move...and you can see it strike. If it is already touching it then back it off until it is just barely making contact. Now turn it in one full turn.

This should be enough to start to the car; if not, turn the idle screw in half turns until it runs, then adjust the mixture and back off the idle screw, over and over, until you have it running mostly on the mixture screw.

At this stage turning the mixture screw will cause the engine to slow down (lean, or turning in) and speed up (rich, or turning out). You want the mixture to be set so that the engine is at the smoothest point of operation and highest speed attainable with the mixture screw. When you find it, turn the idle speed screw down or up to make up for the RPMs to 850.

B

[profcucchi]

You are fine with regards to the screws being in the right place.

The one in the center of your picture, the inset screw, that is your mixture screw.

Above the mixture screw is the base of the carburetor body. It has bolts holding it down, left and right. Just to the right of the right-side bolt is the idle speed adjustment screw. You can just see it hiding in your picture, in the shadows in the right side.

You need to:

Slowly screw the mixture screw in until it stops - don't go further and don't force it - then back it out two full turns.
Slowly screw the idle speed screw in until it makes contact with the throttle lever. You'll know it makes contact because the throttle assembly will start to move...and you can see it strike. If it is already touching it then back it off until it is just barely making contact. Now turn it in one full turn.

This should be enough to start to the car; if not, turn the idle screw in half turns until it runs, then adjust the mixture and back off the idle screw, over and over, until you have it running mostly on the mixture screw.

At this stage turning the mixture screw will cause the engine to slow down (lean, or turning in) and speed up (rich, or turning out). You want the mixture to be set so that the engine is at the smoothest point of operation and highest speed attainable with the mixture screw. When you find it, turn the idle speed screw down or up to make up for the RPMs to 850.

B

That's fantastic, Brad.

My order to Amazon is complete.

[bradartigue]

Thanks!