(this was a techtalk question but I transferred it here n the absence of anyone seeming to know anything about this ancient 1980s tech.

My BDR Twin Dellorto DHLA 45C has Main Jet 180 Air correction 150, 38mm choke,  looks to me (much googling and looking at examples) like this is intended for high airflow and fuel delivery at higher engine speeds.

So to compare to Cosworth's "standard for 170BHP " (issue 2 page 6)

Cosworth               Mine

38         Choke            38

140.       Main Jet.    180

160  Air Correction  150 

So that looks like mine is intended to be intended for wide open throttle / max revs more often than not.

All the examples I see in Des Hamill's book are smaller, but intended to allow round town and general road use i.e. f which I am not looking for.lexibility

ok, so this is jetted for WOT use at the expense of round town and m.p.g. I wonder of my builder was intending to do hill climbs - that would be nice because it's similar to what I like doing. suits me for what you might call Alpine hill climbing for hours on end.

Altitude (O2 density / colder): At lower altitude, more O2 = leaner mixture.  At higher altitude, less O2, = richer mixture. Setting is good for  +/- 500 metres (total 1,000), so temporarily +/- say 1,000 (total 2,000).

So 1,350 (home) setting is good for 1,850 (2,350 temp i.e. 2,000 metres is ok) or 850 (350 temp i.e. 500 metres is ok).

Temperature also impacts air density, it gets 1c cooler for each 100 metres of altitude so one can feel it getting colder. This is working to compensate for the O2 loss and vice versa it gets hotter as one descends, again countering the altitude drop. I suppose this might suggest seasonal tuning changes. 

While one can use all the tuning kit (Colortune, Carbtune Pro, Syncronometer) it may work just to adjust the adjustment screws by set amounts per (say) 500 metres. For example (a quarter turn). N.B.

The syncronometer check should in any case be routine.

Lower Altitudes (e.g. UK) 7484 Main Jet 170 & 175      7485 air corrector jet size 160 & 170
OriginalLy set in and  for the UK: Actuals are Main 180 & Air Correction 150
Higher Altitudes (e.g.CH) 7484 Main Jet 185 & 190.     7485 air corrector jet size 130 & 140

Starter Jets - not crucial, but if use is longer term:
3315 starter jet size 55 Actual is 58 3315 starter jet size 60

Emulsion tubes:
If I was making significant changes to the carburettor setup, such as switching from a very high-performance setup to a much milder one (or vice versa), or if I  was tuning for very extreme (is that tautology?) altitudes (like Peru etc), I would consider the emulsion tubes. But for fine-tuning for different altitudes I don't think they are relevant because they relate to overall fuel delivery characteristics and are selected based on the engine's specific needs and how it breathes.I suppsoe hving complete sets available would make it easier/faster to change over.

To explain the above a bit more here is a picture of the three components that make up the one item involvced when changing the Main Jet IF (big if) the three components are already prepared, the trouble with this is it requires SIXTEEN identical emulsion tubes pre-prepared with all the above tops (air correctors) and bottoms (Main Jets) (costs £240 before carriage). 

So I would need in addition to the ones I have already in use a further sixteen of the 7772.5 emulsion tubes in to which to screw all the variations above, so then it would be trivial to remove 4 and insert 4 of each.

I suppose easy enough to retune at the roadside or easier at the overnight stopover.