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How To Choose The Proper Fuel Pump Pushrod

Discussion in 'COMP Cams Technical Reference Articles' started by jjamros, Mar 23, 2012.

  1. jjamros

    jjamros Guest

    Installing a larger, more aggressive camshaft is a great way to increase horsepower, boost torque and get better performance out your engine. But for everything to work properly and to keep your engine safe, there are other factors that need to be considered, such as valve springs and distributor gear material. If you are upgrading your camshaft in a vehicle equipped with a mechanical fuel pump, you may also need to upgrade your fuel pump pushrod for compatibility with your new cam.
    Many first time engine builders are simply unaware of the need to match camshaft and pushrod materials. But failing to upgrade or selecting the wrong pushrod tip can lead to lobe wear that will damage your new camshaft, void its warranty and send metal shavings through the engine. COMP Cams offers several fuel pump pushrod options that will prevent this damage from occurring and help maximize the power potential of your application.

    Even though it is sometimes overlooked, selecting the correct fuel pump pushrod is actually a very straightforward process. Much like selecting the correct distributor gear, you need to know what material your new camshaft is made from. Is it steel, austemptered ductile iron or cast iron? The material of your fuel pump pushrod must be softer than the material of your camshaft. This allows for proper mating and prevents excessive wear on the cam’s fuel pump lobe. This is true for both flat tappet and roller camshafts. The three most common fuel pump pushrod materials are bronze, steel and ceramic. However, COMP Cams does not recommend ceramic pushrods as they are too easy to accidentally damage before and during installation.

    When a mechanical fuel pump is run with a cast iron camshaft, the OEM steel pushrod is often safe to use. However, it is always a good idea to double check the pushrod material and condition when installing your new cam. Fuel pump pushrods are designed to wear down instead of grinding into the camshaft. Taking the time to replace the pushrod during the cam installation will help prevent problems in the future. COMP Cams carries several stock replacement and high performance steel tipped pushrods if you need to replace a worn stock one or if you no longer have the factory pushrod.

    If you are using a high pressure or high volume fuel pump with a cast iron cam, you will need to upgrade to bronze tipped rods. Performance fuel pumps exert more pressure on the pushrod, which in turn presses harder against the camshaft fuel pump lobe. The bronze tip adds a protective cushion. However, it will need to be checked periodically to ensure the bronze tip has not been worn off, leaving exposed steel rubbing on the lobe.
    Upgrading to a steel roller cam core or austempered ductile iron core requires upgrading the fuel pump pushrod to one with a bronze tip. When the two surfaces rub against each other, the softer bronze tip will ride smoothly across the lobe instead of grinding into the cam material.

    All bronze tipped fuel pump pushrods from COMP Cams are black oxide finished for wear and corrosion resistance. However, this means you have to look carefully to see which end of the pushrod should come in contact with the camshaft. The black oxide does not adhere as well to the bronze tip as it does to the rest of the pushrod. Thus, the end with the thinner, semitransparent coating should face the camshaft.
    Some applications may also require a unique pushrod solution. For example, COMP Cams manufactures a steel rod with roller tip pushrod for Small Block Chevy applications. These blocks have a special area where these unique pushrods are slotted in place to keep the roller tip oriented properly.

    Finally, if your new cam is going in a high performance application that runs very high RPM, a lightweight hollow tube pushrod will help reduce overall mass. COMP Cams carries hollow tube fuel pump pushrods with both steel and bronze tips.

    Correctly matching your fuel pump pushrod to the type of camshaft in your application is an often overlooked yet critical step when building an engine. For assistance in selecting the right fuel pump pushrod for your new cam, call the COMP Cams CAM HELP Line a 1.800.999.0853 or visit www.compcams.com.

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    Last edited by a moderator: May 28, 2014

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