Need Help Identifying Carburetor & Have Tuning Questions

[spider2354]

Hey guys, I've got a couple questions about this carburetor that is on my 76 124. It was on it when I got it, not completely sure that it is the one that it came with or even the one that should be on it. I don't have a way to get any pics up right now so I will do my best to describe everything in hopes that someone can help me figure out what I'm looking at. It is a Weber carburetor and it has a mechanical/manual choke as well as a mechanical secondary. From what I was able to find, not saying that this info is 100%, but if it's got both a mechanical choke & secondary it's supposed to be a 34dmsa...however from the pics I've seen of 34dmsas...it doesn't look like it. I've got two (2) adjustment screws (with springs) on the same side of the carburetor as the diaphram and they are right next to each other..facing the driver fender. Now I also have what I have been told to be the idle jet screw above those and to the left...towards the front of the car. Anyway, the other night it started dying every time I came to a stop. I took the top half of the carburetor off and cleaned out the jets...also found that the secondary barrel had the primary jet in it (found somewhere here on the forum that the primary jet is supposed to be smaller than the secondary so that made sense). Now it runs pretty well but I don't think it's quite right, still got a decent amount of hesitation on take off. If someone can shed some light on this I would really appreciate it, just haven't been able to find anything that looks like the carburetor I've got. Thanks in advance.

[carl]

Can't figure what Weber you have but Webers usually have the model designation stamped on the mounting flange. Could be very hard to see if on the side facing the motor. As to stumble, sounds like your accelerator pump is not working. Easy to check...with motor off and air cleaner lid off, work the carb linkage briskly and you should see gas shooting down into the throttle bore from the pump exit nozzle.

carl

[majicwrench]

I would NOT go swapping jets around on a whim. Put jets back the way you found them unless you know FOR SURE where they go.

How is idle?? Idle/low speed jet is behind that screw in the "upper left", pull it out, TINY hole always plugs, clean er good, piss carb cleaner into hole in carb, make sure when done that idle mix screw (lower screw) affects idle, 1 1/2 turn out from seated should be about right.
If idle/low jet plugs, idle will be rough, will hesitate bad on accel.

[spider2354]

Yes I remember before working the accelerator linkage and the pump was working before...will check that again here shortly, and thanks for the info on where to look for identification. As for the jets...I came across a thread here yesterday that said the lower the number on the jet (in this case 125 vs 150) the smaller the hole is that the fuel actually sprays out of...I can compare the two and can tell that the 150 is bigger and the secondary was supposed to have the bigger jet. I will look into that some more but thanks for the info on the location of the idle jet, I really appreciate both of your responses. Will update here again shortly. Thanks again!

[majicwrench]

Who said secondary has bigger jet?? Did you find that in a chart from weber or Brad??
You are guessing on those jets, there is more in play here than just the jet size. They have an air bleed and an emulsion (sp?) tube as well. If you do not know for sure, put em back.

Keith

[bradartigue]

Yes I remember before working the accelerator linkage and the pump was working before...will check that again here shortly, and thanks for the info on where to look for identification. As for the jets...I came across a thread here yesterday that said the lower the number on the jet (in this case 125 vs 150) the smaller the hole is that the fuel actually sprays out of...I can compare the two and can tell that the 150 is bigger and the secondary was supposed to have the bigger jet. I will look into that some more but thanks for the info on the location of the idle jet, I really appreciate both of your responses. Will update here again shortly. Thanks again!

The secondary having a larger jet is not always the case. Refer to a service manual for the original jetting of the carburetor(s) over the years.

Did you figure out what you have?