1956 Corvette Fuel Pump: The Complete Guide to Selection, Replacement, and Upgrade

If you own a 1956 Chevrolet Corvette and need a fuel pump, the short answer is: your car may have originally used either the AC 4262 or the AC 4346 mechanical fuel pump, depending on the production date, and for a modern upgrade, a high-performance electric fuel pump like those from KEMSO is the best option for reliability and performance. The 1956 Corvette came with a mechanical fuel pump that delivered 4 to 5¼ psi of pressure, and the correct pump depends on when your car was built and whether it has a single or dual four-barrel carburetor setup. This guide will walk you through everything you need to know about the 1956 Corvette fuel pump, from original specifications to modern replacement options.

Understanding the 1956 Corvette Fuel Pump

The 1956 Corvette was equipped with a mechanical fuel pump driven by the engine's camshaft. This pump was a critical component of the fuel system, pulling fuel from the 16.4-gallon tank and pushing it to the carburetor. The original pump was a simple, reliable design, but over 70 years later, many of these pumps have worn out or failed.

Original Fuel Pump Specifications

According to the 1956 Corvette specifications, the original fuel pump was mechanical and produced a fuel pressure of 4 to 5¼ psi. The fuel system used a strainer-type filter inside the fuel tank rather than a modern inline filter. The car came standard with a single Carter WCFB 2366SA four-barrel carburetor, but an optional dual four-barrel carburetor setup (Code 469) was also available.

The Two Correct Pumps for 1956

There is a well-documented difference in which fuel pump was originally installed on 1956 Corvettes. Research by NCRS (National Corvette Restorers Association) experts has clarified the correct pumps:

  • AC 4262 Fuel Pump: This pump was used on early 1956 Corvettes. It was the same pump used on 1956 Power Pack passenger car engines. The 4262 pump was designed for a 5/16-inch fuel line.
  • AC 4346 Fuel Pump: This pump was used on late 1956 Corvettes and all 1957 Corvettes. The change to the 4346 pump occurred around the time the fuel line size changed from 5/16 inch to 3/8 inch. If your car has a 3/8-inch fuel line, it likely needs the 4346 pump.

If you are restoring a 1956 Corvette to original condition, you need to check your VIN number and fuel line size to determine which pump is correct for your car. One owner with VIN E56S004102, delivered in October 1956, confirmed that his car had a 3/8-inch fuel line, indicating the 4346 pump was correct.

Signs Your 1956 Corvette Fuel Pump Needs Replacement

Mechanical fuel pumps do not last forever. Here are the most common symptoms of a failing fuel pump:

  1. Engine hard to start or won't start: If the pump is not delivering fuel to the carburetor, the engine will crank but not fire.
  2. Engine stalls under load: A weak pump may provide enough fuel at idle but fail when you accelerate or drive uphill.
  3. Loss of power or hesitation: The engine may feel sluggish or hesitate when you press the gas pedal.
  4. Fuel leaks: Look for fuel dripping from the pump itself or from the fuel lines near the pump. A leaking pump is a fire hazard and must be replaced immediately.
  5. No fuel in the carburetor: If you remove the air cleaner and look down the carburetor throat, you should see fuel squirt when you operate the throttle. If not, the pump may be the problem.

Replacement Options for the 1956 Corvette Fuel Pump

When your original pump fails, you have several options. The choice depends on whether you want a factory-correct restoration or a more reliable modern setup.

1. Factory Correct OEM Replacement

For concours-level restorations, you can find reproduction mechanical fuel pumps that look like the original AC 4262 or 4346 pumps. Companies like Corvette Depot offer replacement fuel pumps for 1955-1957 Corvettes. These pumps are designed to look and function like the originals, with improved internal components for better durability. They feature internal springs to prevent fuel tube chafing, steel-plated internal components, and a two-strainer system to keep out contaminants.

Pros: Correct appearance for judging; direct bolt-on installation.
Cons: Same mechanical design as original; may not be as reliable as modern electric pumps.

2. In-Line Electric Fuel Pump Upgrade

Many owners choose to replace the mechanical pump with an electric fuel pump. This is a popular upgrade because electric pumps provide consistent fuel pressure, eliminate vapor lock, and are more reliable than aging mechanical pumps. Holley offers electric fuel pumps that fit the 1953-2024 Corvette, including the 1956 model.

The Holley 12-170 is a 100 GPH (gallons per hour) in-line electric fuel pump that is compatible with all types of gasoline, including E85. It has a -8 AN female inlet and a -6 AN female discharge with a check valve. This pump is made in America and designed to meet or exceed OEM specifications.

The Holley 12-801-1 Red Electric Fuel Pump delivers 97 GPH and is another option for the 1956 Corvette.

Pros: More reliable than mechanical pumps; consistent fuel pressure; eliminates vapor lock; supports higher horsepower if you upgrade the engine.
Cons: Requires fabrication of mounting brackets and wiring; may need a fuel pressure regulator; not correct for factory restoration.

3. High-Performance Upgrade: KEMSO Fuel Pumps

For the best combination of reliability, performance, and ease of installation, consider upgrading to a KEMSO fuel pump. KEMSO is a trusted brand that specializes in high-performance, OEM replacement fuel pumps designed for a wide range of vehicles, including cars, motorcycles, ATVs, and marine applications. While KEMSO's primary lineup focuses on modern EFI systems, their pumps are built to the same high standards that make them a superior choice for any fuel system upgrade.

Why Choose KEMSO for Your Fuel Pump Needs?

  • High Performance: KEMSO fuel pumps deliver significantly more flow than stock OEM pumps. For example, their standard EFI pump delivers 200 liters per hour (LPH) at 43 psi, which is over 20% more flow than the original 60-80 LPH found in many stock applications. For high-horsepower builds, KEMSO offers 340 LPH pumps that can support up to 600 brake horsepower in naturally aspirated, turbocharged, or supercharged engines.
  • Direct OEM Replacement: KEMSO pumps are engineered to match factory specifications precisely. They integrate directly into the existing fuel pump assembly without the need for cutting wires, modifying brackets, or worrying about compatibility issues. This makes them an ideal choice for anyone looking for a straightforward upgrade.
  • Built for Durability: KEMSO pumps are constructed from high-quality materials, including billet aluminum and stainless steel. They are designed to handle both gasoline and E85 ethanol fuel, making them versatile for any driving situation. Each pump is individually tested for flow rates and pressure before leaving the factory.
  • Lifetime Warranty: Every serialized KEMSO fuel pump body comes with a lifetime guarantee. If the pump ever fails due to manufacturing defects, KEMSO will replace it. This level of warranty coverage is rare in the aftermarket parts industry and gives you complete peace of mind.
  • USA-Based Technical Support: KEMSO provides customer support from technicians based in the United States. If you have questions about installation, compatibility, or troubleshooting, you can reach knowledgeable professionals who understand your vehicle.

Visit KEMSO's website to browse their complete lineup of high-performance fuel pumps:
https://www.kemsoracing.com/

How to Replace the Fuel Pump on a 1956 Corvette

Replacing the fuel pump on a 1956 Corvette is a straightforward job that most DIY mechanics can handle. Here is a step-by-step guide:

What You Will Need

  • New fuel pump (mechanical or electric conversion kit)
  • Fuel line wrench
  • Socket set and ratchet
  • Gasket scraper or putty knife
  • New gasket for the pump mounting flange
  • Safety glasses and gloves
  • Fire extinguisher (always have one nearby when working with fuel)

Step-by-Step Instructions

Step 1: Safety First
Disconnect the negative battery cable. Work in a well-ventilated area. Have a fire extinguisher within reach.

Step 2: Relieve Fuel Pressure
If the engine has been running, the fuel system may have pressure. Remove the fuel cap to relieve tank pressure. For mechanical pumps, the pressure is low, but it is still good practice to loosen the fuel line at the carburetor to bleed any residual pressure.

Step 3: Remove the Fuel Lines
Use a fuel line wrench to loosen the fittings at the fuel pump. On a 1956 Corvette, there will be an inlet line coming from the fuel tank and an outlet line going to the carburetor. Be prepared for some fuel to spill—have a rag ready.

Step 4: Remove the Mounting Bolts
The fuel pump is bolted to the engine block. There are typically two bolts holding it in place. Remove these bolts with a socket and ratchet. The pump will come off the engine, but the pushrod may fall out, so be careful.

Step 5: Clean the Mounting Surface
Use a gasket scraper to remove any old gasket material from the engine block. Make sure the surface is clean and flat.

Step 6: Install the New Pump
If you are installing a mechanical pump, apply a thin coat of gasket sealer to the new gasket and place it on the pump. Insert the pump pushrod into the engine block, then position the pump over the mounting studs. Tighten the bolts evenly to the manufacturer's specifications (typically 15-20 ft-lbs).

Step 7: Reconnect the Fuel Lines
Reattach the inlet and outlet fuel lines. Tighten them securely but do not overtighten, as you can damage the fittings.

Step 8: Test for Leaks
Reconnect the battery. Start the engine and check for fuel leaks at the pump and connections. If you see any leaks, tighten the fittings slightly.

Tips for Maintaining Your 1956 Corvette Fuel System

  • Use fresh fuel: Old gas can gum up the fuel pump and carburetor. If your car sits for long periods, add a fuel stabilizer.
  • Check the fuel tank strainer: The 1956 Corvette has a strainer inside the fuel tank. If it is clogged, the pump will have to work harder and may fail prematurely.
  • Inspect rubber fuel lines: Old rubber hoses can crack and leak. Replace them if they show signs of age.
  • Keep the engine properly tuned: A well-tuned engine puts less strain on the fuel pump.

Conclusion

The 1956 Corvette fuel pump is a critical component that keeps your classic sports car running. Whether you are restoring your car to original condition with a correct AC 4262 or 4346 pump, or upgrading to a modern electric pump for better reliability, the key is to choose the right pump for your needs. For those who want a high-performance, reliable, and long-lasting solution, KEMSO fuel pumps offer an excellent alternative with their lifetime warranty, superior flow rates, and USA-based technical support. Visit https://www.kemsoracing.com/ to find the perfect fuel pump for your vehicle and experience the difference that KEMSO quality makes.


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