Throttle response can be more important than peak horsepower, especially for most street vehicles, and nothing affects throttle response more than carburetor size. Prior to Quick Fuel Technology’s® (QFT’s) new 450cfm four-barrel carbs, folks with small V8s and 4- and 6-cylinder engines had to work with 600cfm or 650cfm carbs. Regardless of calibration, airflow and fuel curves were rarely optimal.
QFT has solved this dilemma with three new 450cfm models centered around a single die-cast aluminum main body with 1.090” venturis and 1-9/16” throttle plates. There is a mechanical secondary HR-Series, a polished vacuum secondary Slayer model and a Black Diamond® version of the Slayer. These carbs feature normal 4150 modular carb dimensions such as air-horn diameter and baseplate bolt pattern – so they bolt to 4150-flanged intake manifolds and accept traditional four-barrel air cleaners.
QFT’s HR-450 model shows its true performance heritage with mechanical secondaries, dual metering blocks and dual-inlet fuel bowls. The only visible concession to daily street driving is the electric choke. Enthusiasts are already sizing up these carbs as ideal for small-block street tunnel rams. Install the 1:1 Quick-Link™ secondary link for cruise night antics, then swap back to the 40% link for more economical daily driving.
The Slayer SL-450-VS and BD-450-VS offer all of the adjustability of the original Slayer carb and feature the single-inlet, side-hung fuel bowls that make them so adaptable to early muscle cars and O.E. replacements. They both have vacuum secondaries with QFT’s Quick-Set™ single screw adjustment and electric chokes. They are completely adjustable with changeable air bleeds and primary and secondary main jets. The Black Diamond® version lowers fuel temperatures by up to 6% and is scratch and corrosion resistant.
This story was originally published on May 28, 2015. 
