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Discussion Starter #1
Found out I have the 7772.9 emulsion tube in my Dellorto 40s.
Its a 2000 nord engine, standard setup.
Are digging a bit in the carbs now, and cannot find any info about the .9. Seems to be very uncommon.
I need to have the mix screws out 6,5 laps, so was thinking to go up with the emulsion tube size. Hard to do when I do not know where the .9s are....
Air correction 210, main 150. Idle jet is 60, so that should not be bigger.
 

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Here is a bit more information on Dellorto emulsion tubes.

Trying to rank emulsion tubes, lean to rich, is not a straight-forward linear-thinking task, unlike that of idle or main jet selection. The various hole size, number, and distance from the float level and the diameter, length, and position of the 'secondary' barrel contribute more toward the shape of the AF mixture from progression to WOT than overall average AF ratio. Certainly it has an affect on this, but not as straight forward. The main jet and air correction should have a more direct, linear effect*

From this table, the 2000 should have:

Air correction 200 (richer), main 135 (leaner), idle jet is 50(leaner), and 7772.7 idle jet. Interesting that the linked picture doesn't show the '7'.

You might find some interesting reading in that last link. Yes, cranking out the idle screws 6.5 turns to compensate for stumble(?), problems idling(?), or (??) is excessive. What drivebility issue is the problem actually? You didn't state the type of Dellortos either, letter designation, emission, etc. .

* The opinions expressed here are of a novice, who reads much but retains little.
 

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Discussion Starter #3
Well its the same as the one in the link, thanks btw.
Its coming from a non emission Berlina 1971.
So most probably I will go for the .5 to start with.
It needs the 6,5 laps out to go nice on idle, below 4 it dies after some seconds even if the idle adjuster is very far in. On higher rpms it runs like a dream.
 

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Discussion Starter #6
Well yes I agree, they have a bit of everything in there it seems. Its 80 and 7482.3 in the starter, but do not think that would effect the idle.
As it seems that my jettings are on the high side, I am a bit into the teori that the PERHAPS lean emulsion tube will be the bad guy.
Timing, air leaks etc are under control.
 

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Discussion Starter #7
For all curious!

Here comes a picture of the mysterious 7772.9 vs 7772.7, the glittery once are the 7772.7. Feels like a Swiss cheese the 7772.9...
How on earth can they be for emission cars??
 

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