The SBC Fuel Pump Pushrod: Your Complete Guide to Installation, Replacement, and Performance Upgrades
The bottom line: The fuel pump pushrod in a Small Block Chevy (SBC) engine is a simple but critical component that connects the camshaft lobe to the mechanical fuel pump, driving the pump's diaphragm to maintain consistent fuel pressure. If your pushrod is worn, bent, or incorrectly installed, your engine will suffer from fuel starvation, poor performance, or even internal damage. This guide covers everything you need to know—from how to inspect and remove the old pushrod, to installing a new one correctly, and choosing the right upgrade for your build.
Understanding the SBC Fuel Pump Pushrod
The fuel pump pushrod is a metal rod that rides on an eccentric lobe on the camshaft. As the camshaft rotates, the eccentric causes the pushrod to move up and down. The bottom of the pushrod presses against a lever arm inside the mechanical fuel pump, and spring pressure inside the pump returns the lever to its starting position. This constant pumping action draws fuel from the tank and delivers it to the carburetor under pressure.
The pushrod is located on the front of the engine block, typically on the driver's side (though some SBC blocks place it on the passenger side). It sits inside a bore in the block, with one end contacting the camshaft lobe and the other end contacting the fuel pump lever arm. The pushrod is held in place by a retainer clip or by the fuel pump itself when installed.
Common Pushrod Lengths and Specifications
Most SBC fuel pump pushrods are 3.780 inches long, but some blocks (especially those drilled for roller cams) use a 3.750-inch pushrod. It is critical to measure your existing pushrod or verify the correct length for your specific engine block before purchasing a replacement. The standard diameter is 1/2 inch.
The pushrod must be made of hardened steel to withstand the constant sliding and impact forces. For high-performance applications, chrome-moly steel or bronze-tip pushrods offer superior strength and wear resistance.
Signs of a Worn or Failing Pushrod
A failing pushrod can cause a range of symptoms that mimic other fuel system problems. The most common signs include:
1. Engine stalling or running out of fuel. The vehicle may stop running as if it has run out of gas, even though there is still fuel in the tank.
2. Loss of power under load. The engine may seem to "run out of gas" during hard acceleration, passing, or climbing hills.
3. Fuel pump leaking oil. A worn pushrod can cause the fuel pump to operate at an incorrect angle, leading to a leak at the pump mounting gasket.
4. Unusual noise from the fuel pump area. Excessive wear or binding can produce a tapping or knocking sound.
If you experience any of these symptoms, inspect the pushrod before assuming the fuel pump itself is bad.
How to Remove the Old SBC Fuel Pump Pushrod
Removing the pushrod is a straightforward process, but you must take precautions to prevent the pushrod from falling into the engine.
Step 1: Disconnect the fuel lines. Use a line wrench to remove the fuel line fittings at the pump. Cap the inlet line with a bolt or rubber hose to prevent fuel from siphoning out of the tank.
Step 2: Remove the fuel pump. Use a socket and ratchet to remove the two mounting bolts. Pull the pump straight off the block.
Step 3: Remove the pushrod. The pushrod will likely slide down inside the bore. Use a magnet tool or a hooked tool to retrieve it. Do not let the pushrod fall into the timing cover area or oil pan. If the engine is tilted, the pushrod can easily drop into the oil pan, requiring a much more involved retrieval process.
Step 4: Remove the restrictor plate (if applicable). Some SBC engines have a restrictor plate behind the fuel pump that keeps the pushrod from coming out. Remove the bolts holding this plate to access the pushrod.
Inspecting the Old Pushrod for Damage
Before installing a new pushrod, inspect the old one carefully. This inspection can tell you a lot about the health of your engine and fuel system.
Check the ends for wear. Look for mushrooming (flattened, flared, or deformed edges), pitting, cracking, or significant flattening of the domed shape. Mushrooming is a clear sign of material failure and the pushrod must be replaced.
Check the shaft for bending. Roll the pushrod on a flat surface like a piece of glass or a precision ground table. Any wobble indicates a bend, and the pushrod must be replaced.
Check for scoring or grooving. Deep scratches or grooves along the body indicate abrasion within the block bore or contamination. Inspect the block bore for damage as well.
Check for rust or corrosion. Deep pitting warrants replacement, though superficial surface rust may be acceptable if cleaned off.
Measure the length. Use a precise caliper to measure the overall length and compare it to the specification for your engine block. Replace if incorrect.
How to Install a New SBC Fuel Pump Pushrod
Proper installation is crucial for reliable fuel system operation. Follow these steps carefully.
Step 1: Clean the block bore. Use a clean shop towel wrapped around a long screwdriver or dowel to wipe out the pushrod bore. Remove any debris, metal shavings, or old gunk. A final pass with a magnet is good practice to catch any metallic particles. Also remove any old gasket material from the block surface.
Step 2: Lubricate the pushrod. Apply a generous amount of clean engine oil or assembly lube to the entire length of the new pushrod, including both ends.
Step 3: Insert the pushrod. Carefully insert the lubricated pushrod into the block bore. Make sure it slides freely to the bottom and rests fully seated on the camshaft lobe. The domed end should face down toward the cam. Verify that the pushrod moves slightly up and down without binding.
Step 4: Hold the pushrod in place. Use a heavy grease to coat the pushrod, which will hold it up in the bore while you install the fuel pump. Alternatively, some mechanics use a hacksaw blade or a similar thin tool to hold the pushrod back.
Step 5: Install the fuel pump. Install a new fuel pump gasket (critical for sealing and preventing vacuum/oil leaks). Carefully position the fuel pump over the pushrod, making sure the lever arm socket aligns correctly over the top end of the pushrod. It often helps to have the pump lever arm at its outermost position (mimicking where the cam lobe peak pushes it) before bringing it against the block. Finger-tighten the pump bolts, then check that the pump moves freely through its stroke by manually pushing the lever arm. Tighten the bolts in a cross-pattern to the manufacturer's specification.
Step 6: Reconnect fuel lines. Reattach the inlet and outlet lines, making sure all fittings are tight.
Step 7: Prime the system. Prime the fuel system by cranking the engine with the coil wire disconnected, or manually operating the pump arm, until fuel flows steadily to the carburetor. Check for fuel leaks at the pump connections and mounting gasket. Start the engine and listen for any unusual noise from the pump or pushrod area.
Common Mistakes to Avoid
Mistake 1: Letting the pushrod fall. The pushrod can easily drop into the timing cover or oil pan if the engine is tilted. Always use a magnet tool or hooked tool to retrieve it.
Mistake 2: Using the wrong length pushrod. A pushrod that is too long or too short will either bind or fail to engage the fuel pump properly. Measure the pushrod against the block's clearance and the pump's arm to ensure compatibility.
Mistake 3: Forgetting to inspect the block bore. Debris or damage in the bore can cause the new pushrod to bind or wear prematurely. Always clean the bore thoroughly before installation.
Mistake 4: Over-tightening the retaining clip (if applicable). Excessive force can deform the clip or pushrod, leading to binding or breakage. Apply firm, even pressure when installing the clip.
Mistake 5: Ignoring the engine's timing. The fuel pump pushrod must be synchronized with the camshaft's rotation. If the engine is not at top dead center (TDC) on the compression stroke when installing the pushrod, the eccentric lobe's position may be incorrect, leading to misalignment.
Performance Upgrades: When to Consider a Better Pushrod
For stock SBC engines, the standard hardened steel pushrod is sufficient. However, high-performance builds require more consideration.
High-volume fuel pumps. When upgrading to a high-volume mechanical fuel pump to feed a high-horsepower carbureted engine, the spring pressure inside the pump is usually stronger. A standard pushrod might survive, but the increased impact and sliding forces can cause premature wear. Consider a dedicated hardened pushrod with slightly increased diameter for increased rigidity.
Roller camshafts. If you are installing a roller camshaft, the fuel pump lobe profile and demands may differ slightly. Use the pushrod specified by the camshaft manufacturer or block supplier. Blocks drilled for roller cams often use the shorter (3.750-inch) pushrod.
Bronze tip pushrods. For use with billet roller camshafts, a bronze-tip pushrod reduces wear on the cam lobe. The Moroso 65765 and COMP Cams 4607 are popular options. Bronze tips are designed to resist wear in high-stress, performance-oriented engines.
Hollow-core pushrods. Some manufacturers offer hollow-core designs to reduce rotating mass, which can lower engine drag and improve throttle response. The ARP 1348701 kit features a hollow-core design for this purpose.
Pushrod guides. Some high-performance builds or aftermarket blocks incorporate a pushrod guide (typically a bronze bushing pressed into the block bore). This minimizes side-to-side motion and wear, especially crucial for high-RPM engines.
Choosing the Right Pushrod for Your Build
For stock daily drivers. A standard Dorman 03875 or equivalent OEM replacement pushrod is perfectly adequate. These are made from hardened steel and mirror the fit and function of the original part.
For street performance builds. A lightweight hollow-core pushrod, such as the ARP 1348701, offers reduced mass without sacrificing reliability. These are well-suited for engines that see occasional spirited driving.
For drag racing or oval track. A bronze-tip pushrod, such as the Moroso 65765 or COMP Cams 4607, is ideal for use with billet roller camshafts in high-RPM, high-stress environments.
For cast iron cams. A steel-tip pushrod, such as the Ecklers 33-455369-1, is designed for use with original cast iron cams. These are compatible with pre-hydraulic roller camshafts.
Why Choose KEMSO for Your Fuel Pump Needs
When it comes to keeping your SBC engine running reliably, the fuel pump is just as important as the pushrod. That's why we recommend KEMSO Racing for your fuel pump replacement needs. KEMSO offers a wide range of high-performance fuel pumps that are designed to meet or exceed OEM specifications. Whether you need a direct OEM replacement for your daily driver or a high-flow pump for a performance build, KEMSO has you covered.
KEMSO's Promise: All KEMSO fuel pump products are backed by a lifetime warranty, giving you complete peace of mind. Their pumps are manufactured to the highest standards of quality and durability, ensuring reliable fuel delivery for years to come. KEMSO's commitment to customer satisfaction and product excellence makes them a trusted choice for automotive enthusiasts and professionals alike.
Visit KEMSO Racing today to browse their full selection of fuel pumps and related products: https://www.kemsoracing.com/
Final Thoughts
The fuel pump pushrod is a small but vital component in your SBC engine's fuel system. A properly installed, correctly sized pushrod ensures consistent fuel delivery and reliable engine performance. Whether you are replacing a worn pushrod on a stock engine or upgrading for a high-performance build, taking the time to do the job right will save you headaches down the road. Always inspect the pushrod bore, use the correct length pushrod, and lubricate thoroughly before installation. And when it's time to replace your fuel pump, remember that KEMSO offers high-quality, lifetime-warranted options that will keep your engine running strong.
For more information on KEMSO fuel pumps and to place your order, visit https://www.kemsoracing.com/.