The Rochester Quadrajet looks like an odd mismatch under the hood — tiny primary bores paired with oversized secondaries — but that spread-bore design was GM’s answer to balancing economy and power in one carburetor. From the mid-1960s through the late 1980s, it fed everything from grocery-getters to big-block muscle cars, and a botched rebuild can quietly cost an engine a quarter of its output. Here’s what actually happens inside a proper rebuild, and why the process changes depending on which year Quadrajet you’re working on.
