Why not start with the proper jetting for a 1750?

 

I think if you mess with the float setting you're just going to screw up the mixture somewhere else.

Here's what the book says for an Alfa 1750 with a 40 DHLA, no letter.

 

Thank you Gubi , for your fast answer. The floats I have are showing the 7298.2 so the setting must be17 mm .. the 7298.2 float is very rare..

The numbers from your book are also ..a little confuse. The earlier carbs used a smaller Main jet ( 128 vs 135 ) a lear mixture /emulsion tube.. AND weaker pump jets ?? Why ? Doesn´t make sense...
I have 135 main 50 idle with 7772.7 emulsion 7850.3 Idle jet Holder 32 choke 7848.1 venturies 33 pump jet 150 float needle....
and the car runs real good ( besides the rich "area" between 1500-2200 rpm )

I tried the 128main 50 idle..recipe for the earlier 1750.. including the 7772.1 Emulsion tubes... no way -the car is undriveable..

 

Yeah, no idea why they're so different, and not sure what to tell you about the float height, but that's what the book says. Pump jets are weaker but pump volume is larger, so that's probably a wash.

You might be expecting too much from carburetors. They're kind of a blunt instrument in a lot of respects, and it's likely not reasonable to expect them to give a flat AFR under all driving and environmental conditions. If it's diving well it's likely good enough.

 

...yes - perhaps you are right. I will leave the carbs as they are right now. The car rans good so far. And the milage is also o.k.
Thank you for sharing your opinion.

 

update.... two days ago I changed the jetting. From the 2000 to the 1750 numbers. What a difference ! Another car.
Current set up : 135 main. 7772.5 Emulsion tube . 200 Air correction jet 50 idle jet. 7850. 1 idle mix tubes. and 33 - yes 33 not the 40 accelerate jets. Float setting 17mm /25 mm
This is the setup for a 1970 GTV... and works perfect with my 1800 Alfetta engine. The 2000 jetting works....but to be honest, the engine is running too rich.