Rocker Arm Q&A

Q. Can roller rocker arms be rebuilt?

A. 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.


Q. Can I run stock, non-adjustable rocker arms with an aftermarket camshaft?

A. 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.


Q. How much power can I expect to gain when I replace my stock rocker arms with full roller rockers of the same ratio?

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.


Q. Does moving to a higher ratio rocker generally increase performance and what factors should be considered?

A. 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.