Does your Weber DCOE or DCO/SP carburettor hesitate during acceleration?
Does the engine appear to run with a mixture that is too lean at high RPM?
Do you want to understand how the choice of jets affects engine performance?
In all these cases, understanding how the Weber DCOE main circuit works is essential to accurately tune your carburettor and unlock your engine’s full potential.
Through the needle valve (1) — see PAF7950315001 — fuel (shown in yellow) enters the carburettor float chamber. The float (see here) controls the opening of the needle valve (2), maintaining a constant fuel level, which is essential for correct operation of the main circuit.
The fuel then flows towards the emulsion tubes (4) — see PAF6145002700 — where it is mixed with air (shown in blue) supplied through the air corrector jets (3) — see PAF77401.
This air/fuel mixture (shown in green) is then precisely metered before being delivered into the carburettor through the main fuel conduits (5) and auxiliary venturis (6) — see here — which ensure efficient fuel atomisation within the airflow.
Weber DCOE Main Circuit Tuning
The selection of main circuit components — main jets, emulsion tubes, air corrector jets and chokes (diffusers) — directly affects:
- air/fuel mixture richness,
- carburettor progression,
- throttle response,
- engine performance at medium and high load.
Every engine configuration requires a suitable calibration depending on:
- engine displacement,
- camshaft specification,
- compression ratio,
- exhaust system,
- vehicle usage.
Explore our selection of genuine Weber spare parts and calibration components. As an official Weber dealer, we supply authentic Weber main jets, air corrector jets, emulsion tubes and replacement parts for Weber DCOE and DCO/SP carburettors.
Related Weber DCOE Guides
- Weber DCOE Idle Circuit — Understand how fuel delivery changes as engine speed increases.
- Weber DCOE Accelerator Pump Circuit — Learn how additional fuel is supplied during rapid throttle opening.
Genuine Weber Parts from PAFClassic
PAFClassic 🇬🇧 is an official distributor of WEBER carburettors and WEBCON products.
All carburettors supplied by us are genuine WEBER carburettors manufactured in the licensed production facility of Magneti Marelli in Spain.
We have access to more than 11,000 references (carburettors and spare parts), as well as the official WEBER technical library, allowing us to supply the correct components for your carburettor.
Always make sure you purchase genuine WEBER products.
Copies of these legendary carburettors are now widely available on the market. Although often offered at attractive prices, they may have inferior manufacturing quality and are not always compatible with genuine WEBER components. Differences in jet dimensions, internal components and calibration can make correct tuning much more difficult.
