How the tuning differs from conventional carburetors?

The tuning of the main circuit fuel flow curve is vastly simpler than in a booster style carburettor. The unique design of the main jet gives a flat fuel curve through all air flow ranges of operation.

Dyno tests have shown instant flat fuel curves at whatever ratio you select it to be. There is no need to understand complex emulsion well tapers and air bleed influences or other difficult concepts, you simply select a larger jet for more fuel flow. The main jet system is also separated from the transfer system, so altering the main jet size has no influence on the idle and transfer fuel quantity.

Another common problem in conventional carburettors is reducing aeration of the fuel prior to main jet entrance. When the main jet draws in an air bubble instead of fuel, the mixture is altered for a short period of time. TheQuickchange Smart Carby has a unique bowl design that eliminates bowl frothing entering the jets. The bowl also flows much more fuel than a conventional Holley bowl and the fuel flow rate is independent of the needle and seat window alignment. Fuel pressure handling limits are increased and fuel cannot splash into the vent. The fuel system is easily cleanable right up to the window. Float assembly is done without tools and is very quick. The bowl screws are dry assembly, not requiring sealing washers and any bolt contamination can't find its way into the fuel.

Carbies on Blackjack showing fuel bowls. Note: Dash 6 fuel lines fit straight into bowls. No adapters needed. Photo by Lee Davis
Accelerator pump passaging.

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