Volvo RWD 120-130 Forum

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Beginner SU questions. 120-130

As this is my first car with any carburetor of any sort, I'm very much taking the "push this and see what it does" approach to learning how things work, with a fair does of the Swedish Embassy literature thrown in for good measure.

First off: the sw-em site says that when fully choked, the jets should drop down about 1/4". I'm getting about .365" on both jets (digital caliper to the rescue). Is this acceptable or to they need to be adjusted for less travel?

Second: When idling at about half choke with the filters removed, I can visually see fuel droplets/mist originating at the front-carb needle assembly if I lift the dashpots slightly, being drawn down into the engine. I don't see this on the rear carb, or at least to a significantly less noticeable degree. I'm not sure which one is correct, but the fact that they are operating differently tells me something isn't square with one or the other. With the engine off they both seem to pass visual muster and actuation just fine. Any thoughts?








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    Beginner SU questions. 120-130

    Tim;

    The amount they drop is a function of the cable adjustment...and my "about a 1/4inch" is your .365", when armed with a digital caliper! The important thing is you have choke on both carbs, because when its cold, you'll need it to start! ...but, that difference of 0.115" bothers me a lot less than the difference in operation and what you see when lifting the dashpots and peering down their throats...what you are seeing suggests front fuel level / fuel bowl float adjustment is high OR back fuel level / fuel bowl float adjustment is low on back carb...you might want to check and compare those and get them more equal...

    Cheers








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      Beginner SU questions. 120-130

      Thanks. That at least gives me an idea of where to start looking.

      Is there any way to check and see if one is high or the other is low? I guess I could have BOTH conditions simultaneously. What is "normal"?








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        Beginner SU questions. 120-130

        Here is a page that is from the Australian TR Register that has general information on tuning the SUs...
        http://www.tr-register.com.au/Files/sugeneral.html

        Here is a short description of how they work...
        http://www.su-filters.com/sucarbs.html

        Good luck & Cheers!
        OK







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