Low/Rough Idle Question

I hope you find your solution. It is out there. Much useful information above, and it is great you are sharing what you try as you work through this dieseling. In my own, limited experience, the '90's era Weber 32/36s that I rebuilt, responded well and I am very happy at how they perform now. But I would not proceed with any rebuild if I could not deal with throttle shaft vacuum leak. Fortunate to have the Canadian distributor for Weber here in Vancouver, and I installed these inexpensive bearings that eliminate the vacuum leak in older Webers. Yes, may not be your issue, and only part of the process, but these helped me get to the end of the quest for tuned, synchronized, strong idling and no dieseling, pair of Webers. Good luck and keep us updated! Mike
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@bluecoupe30! - can you share the link to that site please?
I'm close to Seattle so shipping from that Vancouver distro would be cheap if I find I need those parts. Thanks.
 
Me again...so going to do a full ignition timing sequence this weekend since an additional 1/8 clockwise turn of the dizyy did not correct the dieseling at shutdown.

Sorry for the noob question but how/where do you adjust the idle so you can get the RPMs to increase to 1700?

I know where the idle speed adjustment screws are for each carb, but since they are synced and share a throttle linkage, do you use the one for the front carb, the rear carb or by other means?
 
how/where do you adjust the idle so you can get the RPMs to increase to 1700?
I know where the idle speed adjustment screws are for each carb, but since they are synced and share a throttle linkage, do you use the one for the front carb, the rear carb or by other means?
It has been a while since I fiddled with a dual carb set up. I believe that if you study the linkage you will find a set screw for your purposes.

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https://e9coupe.com/forum/threads/my-new-strobo-gun-how-to-set-timing-please-help.12400/
https://www.weberperformance.com.au/wp-content/uploads/2024/01/32_36_DGV-Adjustments.pdf
 
For Weber's, the electrical solenoids are supposed to cut fuel (when switched off) to not allow the motor to diesel along after the ignition is cut.
I had a 2002 in California (in the 1980's) and installed a Weber 32/36 DGAV in place of the original Solex carb when I had the motor rebuilt. There was only one CARB compliant carburetor I could install then (other than the OE Solex) and that was a water choke, electrical cutoff solenoid Weber as I noted above. If the car was idling and you pulled the wire off the solenoid - the car quit (at least mine did -and I believe that was the intent).
If yours continues to run after the ignition is switched off - does the power to your solenoids stay energized? Something seems odd here....
 
I have used the 32/26 Weber on numerous vehicles, some of which included an idle shutoff solenoid. Except for an air-cooled application and a boat, they were all equipped with a water choke. Not all of the solenoids were interchangeable. Every so often a weber-equipped engine would inexplicably run rough or even stall or experience a slight run on. This was a general indication that the idle fuel circuit, also containing the solenoid, was plugged with debris. Whether this was from inadequate air or fuel filtration or poorly formulated fuel is not known. The immediate remedy was almost always R&R ‘ing the solenoid and its jet and dousing all related parts and orifices with Gumout or CRC. I vaguely remember experiencing similar situations with Zenith and Solex carburetors - but never as often.


There were a few times where an engine’s symptoms seemed very similar to a blocked idle jet, but to the point of lip277's post, the issues were generally not related to a malfunctioning or disconnected idle shutoff solenoid. Instead they were related to a flooding situation caused by a stuck inlet needle valve or seat, or failing floats or floats that were also stuck or sticking. A worn or neglected accelerator pump diaphragm could also upset the mixture production. Another somewhat related scenario where the shutoff solenoid might be unfairly blamed for erratic engine operation and engine run on is where the throttle plates are not fully returning to the proper idle position due to a maladjusted or sticking fast idle linkage. A similar scenario is where the throttle plates are poorly adjusted likely due to an dubious attempt to achieve an acceptable idle or mid-range operation when the carburetor is improperly jetted or to overcome a host of other engine infirmities such as maladjusted leaky valves, low compression, etc. In any event, these throttle plate settings can bypass or effectively limit the carburetor’s idle circuit and the incorporated a shutoff solenoid.



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