Rocker FAQ

Rockers

Doesn’t the roller tip make the rocker less durable?
The simple answer to this is no, and the reasons are slightly more complicated. Generally the only way a rocker wears down is via the corresponding contact surfaces, which will experience many hundreds of millions of cycles in just a hundred race hours. Focusing maximum load on the valve tip or lash, this single point becomes the most likely candidate as a point of failure. Replacing this single point of contact with our roller tip provides over 1.7 inches of rotating case hardened tool steel, which can increase the lifespan of a roller tip exponentially.

What follow-up procedures are recommended after rocker installation?
Beyond retorquing stands and rechecking the valves after cool down, there are no break-in procedures for these rockers.

How far out (how many revolutions) can the adjuster screw protrude from the rocker body?
No more than three screw revolutions should be used to ensure proper thrust distribution. If more than three screw revolutions are needed for proper connection, it is likely the pushrod length is incorrect.

How much do I torque the adjuster screws?
Adjuster screw jam nuts should be hand tightened as it is only necessary to lock its correct setting position. This is accomplished using the appropriate size box wrench.

How much clearance should there be between the rocker side and thrust washers?
We recommend .010″-.020″ clearance for proper oil flow/lubrication.

Can I add shims between the rocker stand and head if the pushrod does not sit properly in the screw cup?
Shims should only be used to optimize proper geometry with regard to rocker and valve tip. Only after following that procedure can a proper pushrod-to-adjuster cup relationship be determined.

If I’m concerned about over-springing my cam or rocker arm, should I reduce the spring pressure as a safety precaution?
Applying inadequate spring pressure has significant adverse impact on the life of a rocker assembly as well as valve and valve spring. Engines are designed to operate within certain pressure constraints. Depending on cam profile and Engine rpm, insufficient spring pressure can actually cause loss of valve control, which may turn a properly controlled lift-and-lower operating cycle into a destructive jackhammering motion. If you are uncertain, please contact a qualified valve train tech to ensure proper spring pressure is included in your particular engine program.

I keep breaking rockers, should I purchase rockers composed of heavier duty material?
The pressures and load applied to either side of a rocker, if adequate, are not so significant that they should cause a fracture. A broken rocker, while not good news, should be seen as a warning sign providing you the opportunity to find the cause. It is for this reason that simply replacing a broken rocker with a new unit could very likely result in catastrophic damage to a number of corresponding engine components (valve, piston, head, block, etc).

Can I replace just one rocker?
Rockers function in tandem, each one ostensibly experiencing the same wear and level of fatigue. If one unit is fractured, it is likely others may fail as well.  Though it is feasible to replace a single rocker arm, the possibility of future failures remain.

What causes rockers to break (and how are these things prevented)?

Float – Loss of control of the valve train.
Prevention: Coordinating proper lift rates, spring tension, component weights, and RPM.

Coil bind – Exceeding useable travel of the spring as installed.
Prevention: Ensure proper spring/valve travel prior to bind.

Retainer and guide collision – Inadequate retainer to guide clearance.
Prevention: clearance issue at this point must be detected and corrected during initial setup of the heads.

Piston-to-valve contact.
Prevention: Must be considered and corrected if necessary during the planning and pre-assembly stages of the engine (re)build.

Continue to Rocker Info.