[SSDiv6]

[QUOTE=Chris Hill;72195]In general, if you are experiencing rocker arm failure, you are experiencing extreme valvetrain lash during operation. The extreme lash causes very rapid impact loading and the rockerarm fails due to too much stress.{/quote]

Chris, the dynamics are not the same for between a hydraulic or solid lifter.

The rockerarm failing is a result of the valvetrain being asked to do something it was not designed to do, specifically the CAMSHAFT DESIGN was intended for a LOWER RPM given the rest of the valvetrain system.

This may be correct for an OEM cam, however, we are talking about a camshaft that is strictly designed for racing. Yes, the OEM valvetrain can fail with a racing camshaft design. The OEM valvetrain in earlier engines, was not designed for high RPM operation.

Let me try this analogy. You have a wheel and tire combination that is not balanced and the imbalance is very noticeable at 80 mph. From experience, if you run below 80 mph, the imbalance is not very noticeable and nothing in the suspension fails. But the closer you run to 80 mph, the more severe the imbalance becomes and at 80 mph, it feels like the entire wheel and tire is almost jumping off the ground. If you run an extended time at 80 mph, eventually something in the suspension will fail such as a strut, bushing, ball joint, etc. Since wheel and tire imbalance is a well known phenomenon, we instinctively know the root cause of the problem is the imbalanced wheel and tire, not the strut or ball joint that failed.

In the suspension failure above, the failure was the ball joint, but the root cause of the failure was the imbalance in the wheel and tire.

A valvetrain is very similar to the suspension example above, but the “imbalance” in the valvetrain is a fundamental component in the valvetrain that cannot be eliminated. The imbalance is the camshaft design. If the camshaft is designed to operate at a lower rpm, but is operated at a greater rpm, it is just like the imbalanced wheel and tire above. Below a particular rpm, everything is ok, but exceed the specific rpm of the system, all hell breaks loose and valvetrain components begin to fail. With most combinations in stock eliminator, the rockerarm is the weak link and fails due to an improper valvetrain design causing impact stress.

In the valvetrain failure above, the failure is the rocker arm, but the root cause of the failure is the camshaft design for the valvetrain system.

Chris, your analogy cannot be applied here because the dynamics are different. Again, you have to look at the valvetrain from the point of view as a system. By the way, it is not the camshaft design...the lobes I have designed for others, are more gentle in the valvetrain that earlier designs. I have spent many hours plotting lobes in the computer and also graphing lobes from actual measured data with the Cam Doctor. Many of my cams did not break rockers years ago, nevertheless, they have been breaking rockers in the past 3 years. The lobe did not change, however, the quality of the rocker arm did.

If you’ve read this far, I’ll give my take on roller rockers in stock. Stock eliminator is supposed to be difficult. Your not supposed to be quick immediately. The majority of the fast guys have been doing this as their main hobby/pastime/business for the past 20 to 40 years. You cannot and will not duplicate their results unless you spend an extreme amount of money WITH THE RIGHT PEOPLE (Woodro Josey, Jim/Matt Morgan, Bub Whitiker, Don Little, Greg Luniack, Jimmy Bridges, Parson and Meyers, etc) and LISTEN to their advice or you will not be anywhere close to competitive in class.

A few of the engine builders you have mentioned, build engines that are already use a good rocker arm (Mopar and Ford Big Block), some of the other racers have shared they use ealier stuff when they can find it and have also experienced failures.

Rocker arm failure is a result of poor camshaft and or valvetrain design, point blank. Roller rockers would just be a Band-Aid to your larger valvetrain problem. If you are experiencing valvetrain problems, talk to your camshaft/valvetrain guy and try a different grind. Please do not ask for a rule change that is not warranted as an existing LEGAL solution is available, you just have to work at it.

Sincerely,

...and...I stand on the fact that a well designed cam, can and will break rocker arms. Do not compare the your current race engine or your Dad's to other applications. Your V-6 engine does not have the power output of other engines, and your Dad's engine is a big block Mopar, probably running the ductile iron rocker arms.