This carburetor has become very popular with NASCAR and other touring series sanctioning bodies.  The purpose is to restrict the power by restricting the airflow into the engine.  The initial results seemed to produce the desired significant reduction in power with the added benefits of leveling the playing field of performance.  BUT WE WENT TO WORK AND CHANGED ALL THAT!

Whenever a carburetor is sized improperly to the engine (like this one), there are a variety of problems that arise.  The air/fuel circuitry was designed for a low air speed/horsepower application.  When this design is applied to a high air speed situation it produces a rich, poorly emulsified fuel mixture.  VDL Fuel Systems has done extensive dyno and track testing to recalibrate the air/fuel circuitry, accelerator pump circuitry, and idle circuit, producing optimum torque, horsepower, and drivability.

Airflow is of the essence with a restricted carburetor.  VDL Fuel Systems takes every part of this carburetor and maximizes the potential airflow while still operating within the tech parameters.  That is where it gets very tricky.  For whatever reasons, the tech tools have evolved to allow a significant amount of modifications beyond the stock sizing.  From booster dimensions, booster location, and throttle shaft width to venturi height, this carburetor must be custom fit to the tech tools.  The performance gains from these modifications are in the 25 horsepower range!  Obviously not something you can afford to leave on the table.  The other difficult aspect to the dimensional aspect of this carburetor is that each series’ tech seems to vary just a bit, requiring VDL Fuel Systems to build a specific carburetor to each series application!  Now what do you think of your “out of the box” carburetor?

After the parts are machined to the minimum/maximum sizing, they are vibratory polished and re-coated.  Assembly is done to tolerance unobtainable in high volume production.  Boosters are installed to within .001’’ on height, twist, and pitch.  The base plate is matched to the main body.  All gaskets are properly matched to the main body to prevent overhang.  And finally, the throttle plates are adjusted for optimum position on the flow bench.  VDL Fuel Systems produces the absolute best custom-built 390 CFM carburetor available!  Built to your specifications and engine application – not just another “out of the box” carburetor.