Excellent- I am interested to know how they work and any issues with setup as I will be doing the same in the distant future.

 

Without seeing, it's difficult to know why one side was affected and not the other. What condition were the float chamber inlet filters in ?

 

Here are the pictures ( I tried to upload yesterday )

To the best of my knowledge, everything internally is in decent condition. No real wear to be seen; no build up of scale or such. The only thing was that yellow gunk.

I replaced that jet previously. So I'm wondering if the plastic diaphragm is reaction with the gasoline to form the yellow crust. But that makes no sense!

So might it be something in the gasoline itself? Maybe a chemical in the gas that reacting with the air?

It might be still clogged up. I'm wondering if the by pass hose to the second SU carburetor is clogged with the very same yellow gunk and causing the overflow.

I'll test it tomorrow by disconnecting the bypass and individually filling each bowl. If both bowls flow out at the same ratio, the clog is within the bypass.

If that doesn't happen, then the issue is somewhere withing the first SU carb. Perhaps the long needle that inserts itself into the diaphragm jet is clogged.

I don't know and am open to perspectives... clogged up with frustration am I!

 

I've seen that stuff before, it's a combination of rust and old gas. Pretty common.
The gas evaporates leaving behind mess in your photos.

 

The pics aren't very clear on my PC, but Jeff is probably right, you get condensation in the chambers and the moisture content starts off the rust and mixed with the gas can leave a creamy orange rusty gloop. It maybe that only 1 carb had condensation which may answer whey only 1 had the gloop.

You didn't say if the inlet filters were clear or not ?

 

The pictures are kind of dark on my machine too, but I've seen this before.
My theory is it's rust from the tank.
My tank was quite rusty and no matter what filter I put in line, there was always accumulation of rust in the float bowls.
The filters simply allowed finer particles of rust to form in the carburetors.

The finer particles of rust, accompanied with condensation and old gas, reform larger chunks of rust as what you see in the photos.
All this becomes worse if the car is allowed to sit for long periods of time in an uncontrolled environment.
Adding to the fact that the fuel system isn't sealed off form the atmosphere just adds to the problem.

 

Update: had to disassemble the SU again as it would not flow evenly with the other SU carbuerator.

So this is what I found: the jet was cracked. It was old and brittle and needed to be replaced.

It took over two weeks to get the correct jet. The ones available were a type that were 0.0001ths different.

Since the SU was removed, I cleaned everything thoroughly.

Question: why would a cracked jet IMPEDE gas flow?
( If anything, I would suspect MORE gas would flow out due to the crack... )

 

Also:

When replacing the SU carburetor, it has four nuts that gon onto the the bolts mounted onto the manifold. It was easy to get three nuts secured onto the mounts, but there was one area towards the front that was more than challenging.

I lost more than a few nuts trying to get it to twirl onto to the threads with out success. Finally, I glued the washer onto the nut, and then twirled the washer while one finger kept pressure on the nut.
After a few twirls to start it on the the bolt, a wrench finished tightening it down. It took a lot of partial turns with the wrench....