Most roller rocker arms are not rebuildable, however one notable exception is the Pro Magnum series from COMP Cams. These 8650 chromemoly steel rocker arms carry a lifetime guarantee on the rocker bodies and if necessary, can be rebuilt in-house at COMP Cams. They disassemble, inspect, and replace all moving parts such as the roller tip, axle, trunion, and bearings. Essential you receive a brand new set of full roller rocker arms for the fraction of the cost.
Almost every time you should replace the factory rockers when an aftermarket camshaft is installed. Simply put, factory rocker arms are for factory camshafts. Factory rocker arms are not designed to handle the added lift and duration that is produced by a camshaft upgrade. Also, non-adjustable rocker set ups do not allow for adjustment of the rocker arm geometry or lifter preload which will reduce performance and possible damage your engine. One more benefit of an aftermarket rocker arm such as the Pro Magnum series is the super accurate rocker ratio. All engine builders know that factory rockers can vary from their advertised ratio due to mass production techniques.
Typically when you replace a factory rocker arm you will see an average gain of 15HP and more area under the curve. When considering the speed at which your valve train is moving at 6000 rpm, any reduction in friction and heat will obviously promote more power and less wear. A full roller design, such as the Pro Magnum series, incorporates a roller tip and roller trunion bearing to reduce the internal heat that is created at the valve and fulcrum. Combine these features with an ultra-strong 8650 chromemoly steel body and it’s easy to see how advanced a set of COMP Cams rocker arms are compared to the factory units.
The general rule of thump for increasing rocker ratio is: every ratio increase adds approximately .035” increase of lift to the camshaft profile. The end result is a “larger” camshaft profile based on more valve lift and faster opening and closing of the valves. Some things to consider before increasing rocker arm ratio are piston-to-valve clearance, retainer-to-valve guide clearance at max lift, and valve spring coil-bind. If these issues are addressed then yes, a higher rocker ratio is a great way to get more bolt-on performance out of your motor.
Factory valve springs are adequate for stock engines, but as with most factory components, they are mass produced and performance is often secondary to cost. Once you begin to modify an engine it places added stress on every part of the valve train system. When you upgrade your camshaft even to a mild street performance grind, you increase valve lift, opening/closing aggressiveness, duration and the rpm range of your engine. All of these factors directly affect valve movement, which your valve spring is tasked with properly controlling. This is why it is so important to use quality high performance valve springs, retainers and valve locks from a reputable manufacturer. COMP Cams valve springs utilize only the finest wire material available, latest designs and advanced manufacturing processes, yielding the best performing and most durable valve springs in the industry. While it is hard to visually see the difference between a “low buck” valve spring and a quality valve spring, rest assured that your valve train will know the difference. Choosing to save a few dollars on inferior valve springs is a high stakes gamble with serious consequences.
It is important for new valve springs to take a heat-set. Never abuse or run the engine at high rpm when the valve springs are cold. During the installation process use COMP Cams Valve Train Assembly Spray (#106) on the springs, rocker arms and pushrods to supply the necessary lubrication for the initial start-up. Upon initial start-up, limit rpm to 1500-2000 until the temperature has reached operating levels. Shut off the engine and allow the springs to cool to room temperature. This process will help eliminate premature failure and prolong valve spring life.
The most common causes of valve spring failure can be traced to three areas: misapplication, mishandling and improper installation. When selecting valve springs it is necessary to consider camshaft specifics, intended rpm and valve train mass. If you take a valve spring beyond its operating range the results can be catastrophic. All valve springs should be handled with care to avoid stress fractures or scarring of the spring material. Improper installation of a valve spring can cause anything from changes in spring pressures to coil bind issues, ultimately resulting in premature failure. Proper installation and installed height will provide correct seat/open pressures. It is critical that each one of these areas is well thought-out to achieve peak valve spring performance and service life.
COMP Cams offers an extensive line of valve springs, including single, dual, triple, and Beehive designs. For most applications we have springs available which simply drop into place, requiring no additional modifications. Some factory cylinder heads feature small diameter spring pockets and/or tall valve guides which limit the amount of duration and valve lift before retainer-to-valve guide clearance or coil bind becomes an issue. In these cases the spring pocket and/or the valve guide must be modified to make room for a larger diameter valve spring. COMP Cams carries spring pocket cutting tools with detailed instructions to perform this procedure.