Fouled Plugs

[mduck]

I have a '65 911 that is fouling plugs on the passenger side. It appears to be getting too much fuel on one side only. The car has Weber carbs that were rebuilt by Pierce Manifold, and an electric fuel pump with a pressure regulator. Only one side is fouling. any ideas? Thanks!

[304065]

Are you using the original kettering ignition or CDI? What is your fuel pressure? Have you set the float levels?

It might be the drop links off the weber crossbar, but those affect the amount of air each side pulls, and the fuel delivery is proportional to airflow. So I wouldn't start there-- I think you may have a stuck needle valve or float on the passenger side. But a sense of fuel pressure and float levels are necessary to know for sure.

[mduck]

Thanks for the prompt reply and help. I have been traveling and just got back to my computer. I am pretty sure the car has the original ignition but don't know how to tell. It's pretty much all original except for the carbs.

We installed a fuel pressure regulator and have tried all pressure settings and it does not seem to matter which setting it is on - it fouls plugs on the passenger side at all settings. Pierce Manifold in California rebuilt the carbs and after a mechanic spent many hours trying to get it to not foul the plugs I sent the passenger side carb back to Pierce. They said the butterfly screws had been turned two full turns so maybe the mechanic did this. I had hoped their turning the butterfly screws back would fix the problem but it didn't.

I don't know what is done on a rebuild but I assume they set the float levels correctly. If you have to twist off the twisted wires to get into the carbs to set the float levels I don't think this was done because the wires are still twisted together.

How would we know about the needle valve? I don't want this same local mechanic working on it any more because I don't think he knows what he is doing. I have a new guy who seems to know a lot and he recommended new (original) spark plug wires which I have bought but not yet installed. The other mechanic put high dollar wires with metal casings on the car. I had aluminum plates made so the original '65 breather apparatus could be used but it is used for both sides so I don't think this is the problem.

Thanks again for your help!

[Steve@Rennsport]

JMHO,.....

I would not assume anything about how your carbs were set up. Make sure the fuel pressure is at 3.5 psi, then get the float level guage from PMO (for Webers) and check these for yourself as thats one big reason for overly-rich fuel mixtures. This is measured on an idling engine.

If the floats are too high or the fuel pressure is over 3.5 psi, you will get plug fouling so these are the very first things to do.

If the carbs were rebuilt properly, you should have new float needles, however these carbs cannot be set up without a running engine.