Weber Help?

[carsngolf]

I'm having a serious problem with a much too rich mixture in the idle circuit and am casting about for a solution. The engine is a stock 2.0 "E". Carb's are IDTP. Fuel pump is a low pressure type and I have installed a new Holley pressure regulator which is set at 3 lbs. Brand new spark plugs turn sooty black very quickly and the exhaust is very smoky. The float levels are good, jets are clean and all passages have been cleaned. I started with 55 idle jets and am now trying 50's. I replaced the 125 main jets with 110's. Air correction jets are 180 and emulsifier tubes are new F-26's. The car runs, but poorly when the idle mixture and air correction screws are fully closed. Opening either one aggravates the running even more. The last thing for me to try is new air adjusting screws and idle mixture screws but the old ones don't seem to be in bad shape. The "O" rings and cups on the idle mixture screws are new. I hate to waste money on new screws if the seats might be the problem but I have no way of telling. Any suggestions would be gratefully accepted.
Thanks,
Jerry Weiland

[Steve@Rennsport]

Jerry,

Have you check the float levels with the sight glass gauge on all 4 float chambers?

Assuming that your fuel pressure measurements were accurate and IF the float levels are perfect, you might need new needles as they tend to deteriorate with today's fuels and leak.

[911pcars]

Have you checked the float levels?

Using a Synchrometer?

Engine compression?

Your basic setup sounds fine.

Sherwood

[kucharskimb]

I know Steve will feel "honored" that I agree with him... Sounds like fuel is pouring down the throats.

Float levels
Needles/seats

I've had trouble in the past when the float bowl has been empty and then the fuel pump has been turned on. As the float quickly rises up against the needle, something gets jambed and fuel just comes pouring down the throat. I end up having to R&R the needle and all is well.

Another thing that happened to me once was one of the lower check balls for the accelerator pumps got stuck open and fuel just squirted out of that bank's nozzles.

[2.7RACER]

I foresee 45 idle jets in your future.
Make certain the butterflies are fully closed. You will need to remove the carbs and look at the under side. When fully closed the buterflies block all three intermediate holes.
With the butterflies slightly open, the lowest intermediate hole will be visible and flowing fuel.
Only the idle mixture screw hole, below the butterfly should flow fuel during idle.
Air flows through the idle air control screw to the base of the carburetors.
A small amount of air flows past the butterflies, even when fully closed. It isn't a perfect seal.
If the butterfly is open slightly, the lowest intermediate hole will be feeding fuel, and of course air past the butterfly, bypassing the idle mixture control screw and air control screw.
The fact the engine idles somewhat with the mixture and air screws closed indicates the fuel and air is flowing from someplace other than the control screws.
Carefully check the idle jets. The holes in the idle jet is very small (.018"-.022") and plug easily.
The mixture screws and the idle air screws each come to a point. Compare them carefully for signs of broken tips.
Also check the mixture and air holes are clear.
Also be sure the small o ring on the mixture screw is in good condition. It must seal for the fuel to be drawn through the idle fuel mixture port. If in doubt replace the o rings.
In fact check the screws over the intermediate holes. They must be tight, air tight. Also the small o rings at the idle jet screw. All of these must be air tight for the engine to pull fuel.
It's like sucking through a broken straw.
As simple as the Weber idle circuit is, it sure can be a pain.

[911K]

Did you check the float levels with the correct tool so that you could see the levels are right? If not, I would try that first before going any leaner on the mixture. Your original set-up should have been just fine.

[2.7RACER]

Hey Jerry,
How did you make out with your serious carb trouble?