Daul single throat 34s ?, vacuum advance, runninig rich Options

[Hine62]

I've just installed dual 34 carbs (EMPI) with the equalizer tube between both manifolds and can't get a good fuel mixture. (The distributor is vacuum and centrifugal.) Tried both sets of jets. Would timing be causing this problem?? Or maybe I need to connect the vacuum from both carbs to dist?

Any help would be great!

[vw505]

Did you set the floats.

[Hine62]

I didn't know I had to. How are they set?

[rmital]

...could you describe the reason or the sympton of your rich running?
..........or, why do you think it's running rich?? (IMG:style_emoticons/default/confused24.gif)

[Hine62]

White smoke coming out the tail pipe on both sides that smells like raw fuel. We haven't been able to to adjust the carbs to mix better air and fuel better.

[Mike Bellis]

Have you read this?

http://www.redlineweber.com/html/Tech/34_ICT_tunning.htm

(IMG:http://www.914world.com/bbs2/uploads_offsite/www.redlineweber.com-10496-1376846719.1.gif)

[rmital]

White smoke coming out the tail pipe on both sides that smells like raw fuel. We haven't been able to to adjust the carbs to mix better air and fuel better.

...how sure are you that your engine is healthy?? Maybe not the carb's fault??

[Hine62]

Just took off the single carb that ran fine for duals. No problems at all until now.

[pilothyer]

Do you have a way to check the fuel pressure ? Could be that the dual webber ICT carbs a a bit more sensitive to excessive fuel pressure. If it is over 2 psi that may be your problem. Which fuel pump are you using ? If the pressure is ok you most likely need to readjust the float levels.....If gasoline is building up inside the carbs (one or both) it is because the floats are not closing the inlet valve and shutting the fuel off when the bowl is full. You will need to bend the tang a bit so that when the float rises the tang will push the valve closed, while you check that see if the seats and the valves are in good condition. You will need to determine it you have brass or plastic floats before you can get the exact measurement for float adjustment.

[chad newton]

Did you try running more intial timing? Some guys go exactly by the book and sometimes that dosnt work, especially with carborators.

[pilothyer]

Here Is a diagram along with part numbers for your carbs:

http://www.racetep.com/weber/34_ICT.pdf

I really think your problem is that the float bowl or bowls if both carbs, are overfilling........This can be from fuel pressure too high, overriding the float adjustment........or..........the float adjustment itself. There are only 4 screws to be removed to lift the carb top and see.

[ChrisFoley]

What camshaft is in the engine?
Those carbs won't tolerate anything more than the stock camshaft.
IMO the firing order of the engine makes them difficult to tune under the best conditions.

[Hine62]

Thanks for the replies! The fuel pressure was low enough for the single carb, but I will check it again. I may replace the fuel pump anyway because I have no idea what it is. (Its square if that helps...)

The engine did get serviced when it was removed to fix the passenger side hell hole. The cam is original as far as I know. When we took apart the carbs to change the jets everything looked good.

I have believe that either the floats or pump is the problem, because the engine runs and pulls fine in eachgear even with too much fuel. I will look at it tomorrow.

Thanks again for the help. :-)

[rmital]

I didn't know I had to. How are they set?

Would like to be directed to some discription on how one would set the floats?

[pilothyer]

I didn't know I had to. How are they set?

Would like to be directed to some discription on how one would set the floats?

We first need to know if the floats are brass or plastic.........same method of measuring, but different measurement.

[nathansnathan]

Everything I've read about weber 34ict's says you have to run a purely mechanical distributor with them. There's no place on them to get a proper vacuum signiture to run an svda dizzy.

[Eric_Shea]

What size engine?
What cam?
Altitude is 900ft.
What idle jets?
What Main jets?
Air Correction?

Just going through this now with my 40 IDA-3C's and I came up with an excel file to help calculate what you're going to need. I need the engine size and the peak hp RPM to help.

[Hine62]

The engine is a 1.8l with stock cam and svda dist. Air jet 180 and main jet 160.

The vacuum for advancing the dist. is from the manifold.

The carbs have plastic floats and explanation on how adjust them would be great.

hine62

[JoeSharp]

In the diagram form post number 6 above the item number 6 upper is the seat and the item number 6 lower is the needle. The float is number 7. The float has a tab that pushes number 6 lower into number 6 upper and cuts off the fuel supply. You need to bend the tab very carefully to obtain the correct distance from the bottom of the float to the face of the fuel bowel gasket. If the float sets to high in the fuel bowl it will allow to much fuel into the bowl causing it to give a mixture that is too rich.

[pilothyer]

Weber 34 ICT with plastic floats Should be set at 3.6mm for the upper limit, and the bottom at 12.1mm. Remove the top of the carb by removing the screws and gently lift the top off....the gasket should stay with the top. To check if the inlet/shutoff valve is in good order, turn the carb top upside down (so the float closes the valve, and blow into the fuel inlet (where the fuel line was connected) you should NOT be able to blow through it. If you can, the seat and the valve should be replaced (comes in the rebuild kit) If you can't you are good to go. Turn the carb top back over in it's assembled position, with the float hanging down..You measure from the gasket (still on the carb top) down to the top of the float this will be the 12.1 mm measurement......bend the tang till you obtain this measurement. Next lift the float untill the tang just closes the valve (not tightly) and measure from the gasket to the top of the float. Bend the tang to get the upper limit of 3.6 mm. Hope this helps you.

Your fuel pressure should be between 2.5 to 3 psi to be correct for these carbs.