Baseline settings for weber carbs

[Mike_72]

Is there a standard setting to the adjustment screws to start with as a baseline for weber carbs? I just finished rebuilding my carbs on and engine which hasn't run in over a decade and I found that the adjustments were all over the place when I took it apart.

[KTL]

Two turns out is a typical starting point.

This website is a goldmine of info and Paul is a member here on the forum (his name is 1QuickS)

Performance Oriented

Click on the Tech1 and Tech2 links to go into the mine. To say Paul knows a lot about these carbs is a huge understatement!

[Mike_72]

What about the air bypass screw and jam nut? They seem to be all over the place on my carbs also

[obscene]

I leave the air bypass screws closed unless needed.

From Paul:

Initial carburetor settings to be adjusted as follows:
Throttle stop screws adjusted until they just touch the throttle arm and then turn 3/4 full turn.
Idle air correction screws are turned in until they lightly seat and then locked with the 8mm hex nut
Idle mixture screws are turned in until they lightly seat and then turned out 1 3/4 full turns. Be careful! Seating these screws too tightly, especially those after market ones made of brass (use a magnet to check them) may cause them to seize their tip in the throttle body and then twist it off when backing the screw out leaving the hole VERY plugged. The stepped-tip mixture screws as used on IDTP Webers do not suffer this issue.
Connect cross bar linkage and drop links to just snap onto the throttle levers without binding, these will be readjusted later but for initial starting it is handy to have these connected.
Check throttle cross bar and drop links for installation alignment, this topic is covered in Advanced Procedures entitled Throttle Cross Bar Adjustment.

[1QuickS]

Idle air correction screws are typically closed and only opened to provide a fine adjustment of air flow parity at idle. If they are opened much at all it then infers mechanical clearances between throttle shafts and their supporting journal bearings. These clearances result in erratic idling performance which can be quite irritating.

[Mike_72]

I got the car to start using the base settings described above. It wasn't running very well but I think I just discovered why. The regulator on my fuel pump seems to have stuck and I was delivering over 7 psi (max reading on my FP gauge and it was pegged). I would imagine at those pressures I was probably over powering the needle valves and flooding the engine with fuel.

[Mike_72]

Originally Posted by 1QuickS

Idle air correction screws are typically closed and only opened to provide a fine adjustment of air flow parity at idle. If they are opened much at all it then infers mechanical clearances between throttle shafts and their supporting journal bearings. These clearances result in erratic idling performance which can be quite irritating.

Thank you very much for the info it was very helpful in beginning to understand how these carbs operate.