Porsche 914-4 Weber Carb running rich, Weber Carb running rich on #4 only Options

[mturner7]

Hi Everyone,

My car is a 1974, 914-4 with a 2.0L (2056cc) engine. With Weber IDF 44's.
My #4 cylinder is running really rich. All the others are fine.

The Question is: What in the carburetor could most likely cause the plug to foul (Running very rich) like in my case? I've tried to adj the air/fuel mixture screw still no change.

This is what I've done so far:

0) Did a compression check on all cylinders. All ok. (95-100psi) 
1) Changed the plugs.
2) Changed the Cap and Rotor.
3) Changed the plug wires.
4) Verified all the jets are the same.
5) Set the Air flow on each carb, sync'd them
6) I cleaned all the jets with the carb in the car, ran and idled much better.
7) Verified Spark to that Cyl, got a hell of a shock out of it.
8) I'm running Elec-Ignition, Flamethrower Coil, 60,000volts.

After doing all this, the #4 plug still fouls after only about 20 to 30 miles. It has to be the carburetor.

I just pulled the carburetor. Thanks for the help.

[technicalninja]

The 115 mains are the only thing that jumps out at me. 130/135 is more common.

Are you running a WB02?

Are you running a CHT?

What are your readings if you are?

I'd expect 15/1 and HOT from those jets

All of the jets except the mains are original sizes IMO.

Commonly a main jetting change of that magnitude will also require an air correction jet change as well.
The ONLY air correction jets I've seen have all been 200.
I own 3 sets of IDFs now. A pair of 40s and two pair of 44.
One 44 set has 170 mains in it now. Someone was trying to "cheat" around having too big a carburetor with this pair.

Get a WB02 if you don't have one.

Takes most of the guessing out of the equation.

I am gathering jets for tuning now. This is what I'm starting with.

Mains 125/130/135/140.
Airs 180,190,200,210
Idles 45/50/52/55

One thing I've noticed with the used carbs I've purchased is multiple jets are missing their sealing O-rings. These WILL NOT work without the correct O-rings.
If your O-rings are more than 5 years old, they should be replaced. I'd use HBNR AC O-rings in a pinch, but I have thousands of these so it's easy for me.

I'd pull the idles and clean them out for your drivability issue first.

First 30-40% of operation is on these jets, and they are tiny.