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.

[Superhawk996]

@spoke

Yes that location is where the idle jet is at. Just above that on the top of the carb body is where the tiny brass calibrated air hole is that allows air into the idle jet to mix with fuel.

I am curious about the hose vacuum pump setup shown in that graphic.

I had never considered if it could somehow be cleaned by a vacuum and maybe lifting some fluid out of the bowl to wash out debris ? Hmm? Caught in my own trap of “this is the way I’ve always done it”? Unfortunate. Maybe someday I’ll have to try it - I like the concept of drawing crap out vs trying to power it out with compressed air which probably would not have worked for the little rubber chunk he showed. Really interesting. Thanks for sharing that! Let us know how it works if you use that vacuum method.