SBC Fuel Pump Fittings: The Complete Guide to Choosing the Right Connections for Your Small Block Chevy
Understanding SBC Fuel Pump Fitting Basics
Fuel pump fittings are the connection points between your pump and the fuel lines. On SBC engines, the most common fitting types you will encounter are AN (Army-Navy) fittings and NPT (National Pipe Thread) fittings. AN fittings are the standard for performance applications because they seal using a 37-degree flare and provide superior flow characteristics. NPT fittings use tapered threads that rely on thread sealant to prevent leaks.
Most aftermarket mechanical fuel pumps designed for SBC engines come with either -8 AN male fittings or 1/2-inch NPT female ports. The -8 AN fitting has an outer diameter of approximately 1/2 inch and flows enough fuel to support engines making up to 700 horsepower in many cases . Some pumps also use -10 AN fittings for the inlet side, which provide even higher flow capacity for extreme performance applications .
Common SBC Fuel Pump Fitting Configurations
1. -8 AN Inlet and Outlet. This is the most widely used configuration for performance SBC mechanical fuel pumps. Pumps like the Allstar Performance ALL40266 feature -8 AN male inlet and outlet fittings installed directly into the pump body . These fittings thread into the pump using 5/8-18 threads and are clockable, meaning you can rotate the lower section of the pump every 30 degrees to align the fittings with your fuel lines . This configuration is rated at approximately 45 GPH at 7 PSI, which is a realistic working flow rating, not a free-flow rating. In free-flow terms, this is comparable to a 172 GPH pump .
2. 10 AN Inlet with 8 AN Outlet. Some high-flow mechanical pumps, such as the Carter M7900G billet aluminum pump, come with a 10 AN male inlet fitting and an 8 AN male outlet fitting . The larger inlet allows the pump to draw fuel more easily, which is critical when you are pushing 225 GPH at 8.1-9 PSI . However, many users prefer to change the 10 AN inlet to an 8 AN fitting to simplify their fuel system plumbing .
3. 1/2-inch NPT Female Ports. Some mechanical pumps, like the Pro/Cam 9350-A, use 1/2-inch NPT female inlet and outlet ports . This gives you the flexibility to install your own fittings, such as 1/2 NPT to -8 AN adapters, to match your existing fuel line setup. This pump delivers 200 GPH at 15 PSI for high-horsepower builds .
4. 1/4-inch NPT Ports. Standard replacement mechanical pumps for stock or mild SBC engines often use 1/4-inch NPT inlet and outlet ports . These are suitable for engines with 2-barrel or 4-barrel carburetors running at 6 PSI of working pressure. They are less common in performance applications because the smaller port restricts flow.
Choosing the Right Fittings for Your Build
The correct fitting choice depends on your horsepower goals and fuel system layout. Here is a simple guide:
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Stock to 400 horsepower: A standard mechanical pump with 1/4-inch NPT ports or -8 AN fittings is sufficient. The Allstar ALL40266 with -8 AN fittings is a solid choice for sportsman engines up to 700 HP and 8,000 RPM .
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400 to 600 horsepower: Upgrade to a pump with -8 AN inlet and outlet fittings. The Allstar Performance three-valve pump provides 45 GPH at 7 PSI, which is comparable to 172 GPH free flow, and does not require an external fuel pressure regulator . For engines with higher fuel demands, the Carter M7900G billet pump with 10 AN inlet and 8 AN outlet delivers 225 GPH .
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600 horsepower and above: You need a high-flow pump with a 10 AN or larger inlet. The Pro/Cam 9350-A with 1/2-inch NPT ports (which can be adapted to -10 AN) provides 200 GPH at 15 PSI . For serious racing applications, consider a dedicated electric fuel pump setup with -10 AN or -12 AN lines.
Installation Tips for SBC Fuel Pump Fittings
Getting the fittings right during installation prevents leaks and ensures reliable fuel delivery. Follow these practical steps:
1. Use the correct thread sealant. For NPT threads, apply a small amount of thread sealant (PTFE paste or tape) to the male threads only. Do not use Teflon tape on AN fittings, as they seal with the 37-degree flare cone. For AN fittings, tighten them until the flare seats firmly, then give an additional 1/6 to 1/8 turn.
2. Pre-tap the holes when possible. Many performance pumps, including the Allstar ALL40266, use 10-32 self-tapping fasteners. Pre-tapping the holes with a standard 10-32 tap makes installation much easier and reduces the risk of stripping the threads .
3. Check pump arm alignment. Mechanical fuel pumps are operated by a pushrod that rides on the camshaft. The pump arm must be properly aligned with the pushrod. If you are installing a new pump, use a fuel pump pushrod and check that the arm moves freely .
4. Use the correct gaskets and mounting plate. The fuel pump mounting plate and gaskets are critical for proper sealing. A typical SBC mechanical fuel pump install kit includes a pushrod, ARP hex bolt kit, zinc-coated mounting plate, and both needed gaskets . Always replace these parts when changing the pump.
5. Verify clockable positions. Some pumps allow you to rotate the lower section to align the fittings with your fuel lines. The Allstar pump is clockable every 30 degrees . Before tightening everything down, test-fit the pump and rotate the lower section to find the best orientation for your fuel line routing.
Why Fitting Size Matters for Fuel Delivery
The size of your fuel pump fittings directly affects how much fuel your engine can get. A pump rated at 45 GPH at 7 PSI is not a free-flow rating; it is the actual working flow under pressure. This is comparable to a pump with a 172 GPH free-flow rating . Using the wrong fittings can restrict flow, causing the pump to work harder than it needs to.
For example, a pump with -8 AN fittings will flow significantly more fuel than one with 1/4-inch NPT ports, even if the pump internals are identical. The higher the horsepower, the more critical it is to have large-diameter fittings and fuel lines. For engines making over 500 horsepower, -8 AN is the minimum recommended size for both inlet and outlet .
Why You Should Choose KEMSO for Your SBC Fuel Pump
When it comes time to replace your SBC fuel pump, you want a part that delivers reliable performance and long-term peace of mind. KEMSO fuel pumps are designed to meet the highest standards of quality and durability. Every KEMSO pump is a high-performance, OEM replacement unit, meaning it matches or exceeds the original equipment specifications for flow rate and pressure. This ensures your engine gets the precise fuel delivery it needs for optimal power and efficiency .
What sets KEMSO apart is our commitment to quality backed by a lifetime warranty. We stand behind every pump we sell because we believe in the quality of our products. Whether you drive a sedan, SUV, motorcycle, or powersports vehicle, KEMSO has a fuel pump engineered to fit your application perfectly. Our pumps are built to withstand the demands of daily driving, and we offer competitive pricing—many models are available for just $79.98 .
KEMSO fuel pumps are engineered to support up to 600 horsepower in naturally aspirated, turbocharged, and supercharged applications. They are compatible with gasoline and E85 ethanol blends, making them ideal for flex fuel vehicles. The pumps feature a bypass valve set at 125.8 psi, which is higher than many standard pumps. This ensures that your engine gets the fuel it needs even under high-demand conditions. The construction of KEMSO pumps uses aerospace-grade materials and ceramic-coated internals, making them resistant to corrosion and wear. Independent testing shows that KEMSO pumps can last up to 15,000 hours of continuous operation, which is nearly double the lifespan of many OEM pumps .
Every KEMSO fuel pump comes with a lifetime warranty. The pump body is serialized, which guarantees that the warranty is valid for as long as you own the pump. This is a significant advantage over standard aftermarket pumps that typically offer only one to three years of coverage. KEMSO stands behind their products with confidence, and their U.S.-based support team is available to help with any questions or issues .
Visit our online store today to find the exact KEMSO fuel pump for your vehicle. Browse our catalog of best sellers, including pumps for popular models like the Subaru Impreza (1998-2023), Honda Civic Del Sol (1993-1997), and Kawasaki Jet Ski Ultra 310LX (2020-2023). We ship directly from our facility in Houston, TX, and our customer support team is ready to help you find the right part. Get your KEMSO fuel pump now at: https://www.kemsoracing.com/