Weber Modifications

[SteveF_911]

I have had these Weber's on my car for about 4 years. I bought them second hand off a guy who had used them on his 2.4 race car.

When I bought them he told me they had been modified by his mechanic. I was no sure what the change was for a couple of years until I compared my Weber's with a friend.

I have attached some pictures of the modifications maybe someone would like to comment.

The problem I have is that no. 4 cylinder has decided to go rich on me.

At first I thought it may have been a bad plug lead but I have recently changed leads and the problem still exists.

It is a intermittent fault.

I have tried.

Float level fine in garage anyway
Carbs sync well.
Car idles well.
Problem mostly ocures on the race track when the car is warmed up and I give it a boot full.

Any thoughts my good friends.

[dvkk]

What are the mods we're looking at?

[aturboman]

The air corrector and emulsion tube set-up is different than any other 3 barrel IDA I've ever seen. They are usually seperate pieces. The emulsion tube usually drops into the body of the carb and the air corrector screws in above it. The ones in your picture look like the style used on 2 barrel IDA/IDF carbs, where they are an assembly. Perhaps that is the modification you are refering to.

[SteveF_911]

Correct aturboman on the jet and emulsion tube modification.

I was told it is a DCOE modification.

Has anyone ever done or seen one of these modifications, or do I have the ony one in existance?

[aturboman]

Its been a while since I have "played" with Webers but I know that on some race applications you can run into a fuel supply issue. On three barrel models one float provides fuel for two barrels and the other a single barrel. I have seen the side that feeds two cylinders run low on fuel under extreme loads. Perhaps the opposite is happening where your single feed float is over supplying that one cylinder. These carbs can be converted to a return style system with out a float or a balance port can be created between the float chambers to share fuel availabilty evenly, either will help retify the issue. Both of these mods are a bit to involved to discuss here.
By the look of your jet stack it appears the main jet is now on the bottom instad of on the holder in the side of the carb as it is stock. On the cylinder running rich, if it is supplied by the one float chamber try droping one main jet size and see if it helps. I would make sure all other factors are emininated first before blaming the carb. Flattening cam lobe, burned valve/seat, weak valve spring, excessive leak down, igntion problem etc.. Best of luck.