Weber help

356robo · 02-04-2011, 03:52 PM

I believe I have a clogged idle circuit on #3 cylinder. When I cover the velocity stack, sealing off the air supply, no change in idle speed. What is the correct procedure to clean out the idle circuit passages with compressed air? Where are the orificies that need clearing?

Thanks in advance,

Rob

5:04 · 02-04-2011, 04:26 PM

I was having a major issue with popping and a stutter after driving through a dirt road. It seemed as though my jets were clogged. I cleaned them and they did nothing so I decided to clean the passages. What I did was to take everything I could off of the fully assembled carburetor and I took canned compressed air and blew it through every hole I could. After that the car ran like a champ. My car sat for the past month and a half so I'll be doing that again tonight in preparation for the track tomorrow.

1QuickS · 02-04-2011, 04:44 PM

Pull the idle jet and check for blockage with a magnifying glass. Typically crud that enters the fuel bowl will find its way to the idle jet which has the SMALLEST metering orifice in the Weber carb. Check out this link for "Sources of Debris in the Float Wells" for more info on this topic:
Weber Carbs Technical

If the idle jet is clear of crud then check the threaded end of the main jet for blockage as all fuel delivered to the carb must pass from the float well through the main jet.

The fuel passage ways (galleries) routinely have inside diameters far exceeding those of the jet diameters so check the jets first. There is one passageway that has a stepped diameter and that is the one from the bottom of the emulsion tube well and that one supplies the fuel that is delivered to the inlet of the idle jet. To blow this gallery clear you must: remove the top cover of the carb (to avoid crushing the fuel floats with compressed air); remove the idle jet; remove the main jet; remove the auxiliary venturi; block the air correction jet with one finger (the jet above the emulsion tube); block the hole uncovered when the auxiliary venturi was removed with another finger; and blow air into the orifice for the idle jet. This will clear the stepped bore in the fuel gallery from the emulsion tube well to the idle jet.

356robo · 02-04-2011, 06:18 PM

Thanks for the responses.

Paul, do you have a photo showing all of these jets, plugs, and orificies? The typical Weber photo/diagram is actually shot from the wrong side of the carburator because the location of all of the parts is difficult to locate.

Thank you,

Rob

MrJTP · 02-05-2011, 07:41 AM

Try this:

http://home.comcast.net/~Ekchuah/Weber.html

Quickstep192 · Quickstep192's Garage

I don't know what this is worth, but I'll throw it out there anyway.

I have two motors with carburetors; a pre-ethanol outboard and the 911 with Webers.
On both, I would have sputtering issues which were resolved by cleaning the carbs, but the problems returned after a couple of weeks without regular use. For right or wrong, I convinced myself that the ethanol gas was eating my fuel lines and that the "goo" from that was clogging the jets. I replaced the fuel lines in both with alcohol resistant lines. (In the 911 I used grade A1 marine fuel hose). I haven't had problems since, but the acid test will be after both have sat for the winter.

356robo · 02-08-2011, 04:45 PM

UPDATE.....

I cleared #3 float bowl and idle jet. Adjusted all floats. Balanced each barrel of both carbs. Balanced side to side. Adjusted idle mixture screws (I think). Here's my problem: I can get it to idle at about 1200, but when I try to lower the idle using the idle screws, the idle falls though 900 to 600-700.

Help please,

Rob