Carburadores weber

Selection and tuning of Weber DCOE carburettors
A very popular modification for RH7 owners is the fitment of twin Weber DCOE or DCO/SP carburettors; these not only deliver the goods but also look very good. A good deal of mystique surrounds Webers, specifically Weber jetting and tuning. However Weber DCO series carbs are not as complicated as you might imagine, and whereas there is no substitute for a good rolling road session to tune them, there is much you can do to tune them yourself, by selecting the correct choke sizes and initial jet settings according to a fairly simple set of rules. This should get the engine running to a reasonable standard in preparation for the rolling road. Arriving at the correct carb/venturi size When selecting Webers, the most commonly asked question is "Should I have 40s or 45s" coupled with "Surely the 45s will give more power". This shows a basic misunderstanding of the construction and principles of operation of the DCO series. It is not the barrel size (40 or 45) which determines the airflow and therefore potential horsepower; it is the size of the main venturi or choke. Selection of the correct main venturi size is the first step in selecting the carburettor. It is easy to make the assumption that biggest is best when selecting a main venturi size, but the purpose of the main venturi is to increase the vacuum acting on the main jet in order to draw in and effectively atomise the fuel mixture. The smaller the main venturi, the more effective this action is, but a smaller venturi will inhibit flow. A large venturi may give more power right at the top end of the power band, but will give this at the expense of lower RPM tractability. Only a circuit racer will benefit from this sort of compromise, on a road car, driveability is much more important. 95 percent of the time, a road engine is nowhere near its peak power, but is near its peak torque for 75 percent of the time. It is much more important therefore to select the main