Volume I, Issue 4, Page 47

What we have here is a staple of American automotive history. holley carbItís a basic 600cfm Holley four-barrel, vacuum secondary carburetor with half a decade of accumulated shop crud. The Holley 600cfm vacuum secondary four-barrel (PN 0-1850) offers a good balance of performance and fuel economy on most small block-powered street machines, and used examples can be found on shop shelves and at swap meets around the country. With the availability and price being attainable, we thought Holley's little workhorse would be a good candidate for a Quick Fuel upgrade.

spray clean your carb Start with a good carb cleaner, such as Justice Brothers, to remove built up gunk and dirt.

Our donor four-barrel was a pretty basic carb, tuned more for economy than performance. To increase its performance we decided to upgrade the Holley with a new QFT adjustable billet vacuum secondary module, which allows you to regulate when the secondary throttle plates open, giving the driver added control over fuel economy and power. Originally, our Holley used only one metering block on the primary side while the secondary side made due with a drilled metering plate located inside the bowl. By adding billet metering blocks to both sides, we both improved the fuel flow and provided the ability to change secondary metering to allow for improved performance tuning. By machining the blocks from billet, QFT eliminates the porosity and surface imperfections that cause cross-well bleeding and lost performance in many cast metering blocks.

Here's What's New!