Rocker Failure

[Schlok]

Originally Posted by CFD

I had two rocker failures then went to the Comp trunion upgrade and had many failures. Scrapped it all and went LLSR with T&D rockers, so far so good.

What's a set of those parts cost? PM if necessary. thanks!

[CFD]

Originally Posted by Schlok

What's a set of those parts cost? PM if necessary. thanks!

You would have to change almost everything cam/valve train related and solid rollers aren't for everyone but off the top of my head my set up was 3,000.00-3,500.00 plus $500.00 to machine the block for the large dia. lifters. That is with changing everything.

[Qfastvette]

I need to know what is the right way to go because I am getting ready to get all my parts Head, Cam, Push Rods and Comp Trunion put on my car next month?

[Stephen12ZL1]

the first question my tuner asked me when I arrived for the dyno tune is "I hope you didn't upgrade the rockers". He was relieved to hear that my rockers remained stock. Seems counterintuitive but reality is leave the stockers and trust they will be fine.

[CFD]

Some cam profiles are more harsh on valve train components so that is something to consider. If I were running hydraulics again I would definitely go with bushings.

[JusticePete]

Originally Posted by CFD

Some cam profiles are more harsh on valve train components so that is something to consider.

You raise a key point. Violent cams produce great numbers, but they are hard on the valve train. Race engines spend countless hours on a spintron where they tune the valve train. Everything from lifters to pushrods, to rockers and springs are tuned, adjusted, to smooth out operation, to improve reliability and durability.

This is rarely done with aftermarket cam installations. It is even more rare with a custom grind cam. If you spend time in a high end race shop, you walk away wondering how most aftermarket cam installations are as trouble free as they are. This is an old video from COMP, but it gives you a decent idea of what they do with the spintron



Pushrods bend, flex, like the pole a pole vaulter uses. Tuning is an effort to have the lifter follow the cam shaft smoothly and the pushrod follow the lifter and the rocker follow the pushrod and the valve stem tip follow the rocker while the spring remains in constant contact without getting loose, floating. Any change to this ballet, a change as small as the weight of the rocker assembly alters the relationship of every component.

I am not a cam expert and don't pretend to be one. I did sleep at a Holiday Inn last night and I do work with experts that build NASCAR cup motors and have incredible expertise in valve train development

[CFD]

rockers and lifters receive the most punishment. Needle bearings are designed to rotate while revolving around the axis. This insures adequate lubrication and good wear characteristics. In the case of rockers this does not happen efficiently. Add to that harsh cam profiles you now have the lifter chasing the cam lobes, every time they loose each other it's like a little hammer on the bearings so you can increase seat pressure but now you face pushrod flex, more load on the bearings and spring fatigue. You also have the chance of a lifter turning in the bore, even the slightest possible amount cause bearing fatigue and can cause premature lifter failure. Then, with a hydraulic lifter the chances of the above happening is even greater because of the limitations of the lifter itself. When you run near/at or slightly above redline what do you expect. lol