dual - single weber carb venturi question

The flow of air/fuel mixture is limited by things like valve size, cc, flow path, etc, as well as the carb. If the carbs were flowing less than their maximum volume in a specific application, then a single carb may be capable of given full flow where twin carbs were used originally. If the carbs were flowing something near their limits, you'd either have to go for bigger chokes/jets (if it's close to the limit) or go for a bigger carb. Usually it's best to speak to tuners who have some experience (and success) in tuning the sort of engine you're interested in. (in my case, - aircooled VW engines, John Maher is the man)

-- athomik

The venturi size normally stays the same. The air flow though the carbs is not constant, but in pulses. If one throat feeds 1 cylinder, 1 pulse will take place every 2 engine revs, and if one throat feeds all four cylinders,

1 pulse will take place every 1/2 engine rev. The max flow durring the pulse is limited by the venturi size.

Bill, '67 bug.

A single large carb is a whole different thing than simple math extrapolated from a dual-carb setup. For one thing, the Type-1 is quite unhappy with a large intake manifold and large carb, except at high RPMs. It's a positive b*ch to make a big single carb streetable. The major problem derives from the single large-carb manifold which is long and fat and thus makes very low air/gas velocity. Mixture suffers. Mileage suffers. Low end suffers. Everything suffers. Except at high RPM.

So, it's best for you to post exactly what configuration you have and how you use the engine, then take recommendations people who have the same, or very nearly the same config with a single carb. Try

and ask in the drag-racing/speed forum. Andaccept no rumor, hearsay, speculation.

Well I changed the vents in my config.. and it seems as though the optimal jetting settings under the 32mm vents are the same as under the 28mm vents. It runs 100000000000 times better now. finally something drivable...!!!