Need Help. Webers running rich

[Bill D]

302 ford
11:5 compression
#61 idle fuel jets
#120 idle air jets


What can I do to lean it out?

Thanks.Bill D

[CompClassics]

Need more info……

1) choke size

2) idle jet holder

3) idle jet

4) emulsion tube #

5) main jet

6) air corrector

[1795]

Bill,

In addition to what Comp Classics asked for, it might be of value to know what your timing is and what your idle rpms are.

I would check your idle jet holders to verify that the air hole is not plugged. I had one of mine that was plugged with some solder.

What is telling you that it is running rich at idle? O2 sensor, smell of gas, fouled out plugs?

Jim

[CompClassics]

I was going to mention timing but I figured I would start with the basic basics first. One that I definitely forgot to mention is FUEL PRESSURE,

[t walgamuth]

float level in all carbs needs to be correct to get good performance.

[Bill D]

Geez, I thought this was going to be easy.mi have no idea what’s what or what size they are.

[CompClassics]

Who did you get the system from?

[Bill D]

Bought the manifold from one company and the Webers from Weber carbs direct

[vntgspd]

In addition to the requests above...

1. Is it running rich at idle and cruising under 2500rpm?
2. Is it rich under heavy throttle and over 3000rpm?
3. All the above

[HighPlainsDrifter]

Hi,
You need a camshaft that has less duration on the intake side otherwise air velocity will be non existent and can even have reversion into intake. You need a weber friendly cam before you band aid the engine.
Perry

[1795]

Originally Posted by Bill D

Bought the manifold from one company and the Webers from Weber carbs direct

Bill,

Check your paperwork that came with the carbs, there should be something there saying what the setup is. If not, contact Weber Carbs Direct and they should be able to tell you. Then post that information here and we can begin the process. Where did you get your cam from and what are the specs on it?

By the way, your fuel pressure should be around 3-3.5 psi. Some people go up to 4, but that is pushing it, especially on a street engine.

There are enough people here with knowledge, we'll get this figured out.

Jim

[1795]

Bill,

How long ago did you purchase the carbs and from what source directly? I tried to go to their website online to see if I could find some information for you with no luck. If you do not have any information from them, you can remove the main jets and idle jets and their holders by unscrewing the screen on the top of one carb and then using a screw driver to remove them. The jets and holders should have numbers on them, telling you what size they are. You can measure the choke tube inside the carb and that number should be in mm. 48 IDA's are the base size and would be fine on a 427 race engine, but are way too big for a 289/302. While my 289 race engine has 48 IDA's on it, the chokes are actually 42 mm. Some street setups may use 38 mm, 40 mm or 42 mm chokes.

Jim

[1795]

Bill,

Heer is an example of my initial setup. I am not saying that you should have this setup, this is just to provide you with an idea of some of the items and numbers that people are asking about. You may end up with similar parts to this list, but i would not suggest replicating this as it was setup for racing.

Webers are easy to take apart and configure. If you do end up needing different jets, holders, chokes, etc. Pierce Manifold is a good source, and they are in CA. When you take the screen off there will be two sets of jets there, two for each barrel. The large screw head is for the primary jet and the small one is for the idle jet.

Jim

Jim

[Bill D]

2 psi

[1795]

Bill,

2 psi is too low, you should be up around 3 psi. With that being said, I am not sure that low psi would lead to running rich, it would seem to lead more to running lean. I defer to someone with more knowledge than I.

Jim

[PDUB]

Probably would be better in the Weber Tuning Forum... not sure if it can be moved.

[Bill D]

I found an online parts breakdown picture of the 48 IDA. looks like I have to disassemble one to see what size parts are inside. I don’t feel at all comfortable doing this. Not sure what my next step is going to be. So close to the finish line and now this. I should have just gone with a 4 bbl carb.

[Bill D]

I wish I knew someone nearby that I could pay to troubleshoot my problem.

[CompClassics]

Unfortunately I am at the other end of the state.
Webers are easier than they appear, just think of aesch 1/2 of int of the carburetors as a single barrel carburetor and connected by a common float bowl. Here are a couple of easy checks to give us an idea of your numbers.
Remove the screen that is located between the two velocity stacks, there you will see four brass flat head type fasteners. Remove two of the brass screw looking fasteners from one side, one will have a hole in the middle of the flat head screw the other will be smaller and have no hole. The one with no hole in the flat screw head is the idle jet holder, attached to it is the idle jet There will be numbers and letters stamped into both of these brass pieces. Next the flat blade head with the hole in the center, there is four pieces associated with this part, the holder Which does nothing but hold the assembly in position, the main jet which is the tapered part at the bottom, the air corrector which is located inside the part that was described first and lastly the emulsion tube the long part with all the holes in it. All of these parts will have stamped letters and numbers. Both the idle jet assembly and the emulsion tube assembly come apart by sliding them apart, try not to use pliers as this can damage stamped number areas or sealing surfaces. These two assemblies are easy to remove for tuning the carburetors.
The last part is the choke, the big round barrel part in the exploded diagram located below the auxiliary Venturi. You should be able to look down the top of the carburetor barrel and note the number that is cast or stamped into the top edge without having to disassemble the carburetor.

[1795]

Bill,

Here is a youtube video showing how to assemble a 48 IDA and it names the parts that we are talking about. At about 5:40 it sows the installation of the main jets and idle jets and their holders. You would be basically doing the same in reverse. It is quite easy, I have changed out all 8 while tuning in about 10 minutes. A flat blade screw driver is all you need. And for now, all you need is to remove one main jet and it's holder and one idle jet and it's holder.

Wish I were able to be there to help.

https://youtu.be/jp_3OjwmmK8

Good luck Bill, based on your skill set this should be no problem.

Jim