SKU: HLY6-522
UPC: 090127684191
MPN: 6-522
The Holley 6-522 is a .130in fuel inlet needle and seat assembly built to control how gasoline enters the carburetor float bowl. It fits Holley 4150 and 4160 carburetors and serves anyone rebuilding, refreshing, or upgrading the fuel side of a street or performance setup. The needle rides against the seat to open and close fuel flow as the float moves, which keeps the bowl at the right level under varying demand. With a .130in seat orifice, this size handles higher fuel volume than smaller restrictor seats, making it a common choice for engines that pull more fuel at speed. It's a small part that has an outsized effect on idle quality and drivability.
The defining feature here is the Viton tip on the needle. Viton resists swelling and breakdown from modern pump gas, ethanol blends, and additives far better than older rubber-tipped needles, so the assembly holds a clean shutoff over a longer service life. The .130in seat opening flows enough fuel for engines that run hard, while the spring-loaded needle damps against fuel slosh and vibration that would otherwise cause flooding or erratic float levels. The assembly threads into the fuel bowl in place of the original seat and works with the standard Holley adjustable float arrangement. Pair it with a fresh gasket during any rebuild, and confirm float level after installation so the new seat geometry seats correctly against the needle.
Reach for the 6-522 when you're rebuilding a Holley carb, chasing a flooding condition, or stepping up seat size to feed a higher-output engine. It drops into a typical refresh alongside a new float, power valve, and gaskets, and it's a sensible swap any time you switch to ethanol-blended fuel. We stock the related needle and seat assemblies, Holley floats, and power valves you'll want on the bench for the same job, plus the broader air and fuel parts that round out a carburetor rebuild.
The 6-522 is a fuel inlet needle and seat assembly for Holley 4150 and 4160 carburetors. It threads into the fuel bowl in place of the original seat and works with the standard Holley adjustable float setup found on those carbs.
Viton resists swelling and chemical breakdown from ethanol-blended fuels and modern additives far better than older rubber needle tips. That means a cleaner shutoff and longer service life, which is why a Viton-tipped needle is the preferred choice for engines running today's pump gas.
The .130in figure is the seat orifice diameter, which controls fuel flow into the bowl. A larger seat like .130in flows more fuel than smaller restrictor sizes, making it suited to higher-output engines that demand more fuel at higher RPM.
Yes. Any time you replace a needle and seat, confirm and adjust the float level afterward so the float closes the new needle at the correct fuel height. Skipping this step can leave the bowl too high or too low, hurting idle quality and drivability.
When you're already in the fuel bowl, it's common to refresh the float, bowl gaskets, and power valve at the same time. Doing the full set together gives you a clean, predictable fuel circuit rather than chasing one component at a time.
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