Breaking aluminum rocker arms

[nokones]

Currently, I am using the T&D Machine Shaft Aluminum Rocker Arms on my SBC 427 with the AFR 245 heads in my 89 C4 Corvette. The car is just an autocross car. The motor will spin up to almost 8,000 RPMs but, I have the rev limiter set for 7, 000 RPMs. I keep breaking the rockers. T&D did repair one assembly a couple months ago. Is this a common problem with Aluminum Rocker Arms? It will probably be best to just scrap the aluminum rockers and go with the Steel Billet Rocker Arms. I was just curious on what are the thoughts on the Aluminum rockers. Are they just wrong product for my application or maybe the wrong Rocker Arm supplier. Comments please.

[andrewb70]

I would double check all of your valve train geometry.

Andrew

[nokones]

The heads were originally setup by Gromm and rebuilt by Lingenfelter. I contacted T&D today and Sheldon told me that the aluminum rockers don't like a lot of idling and low RPMs that normally occur in an autocross environment. He said if I was road racing where the engine was constantly on the high end my rockers probably would survive longer. He said the idling and low RPMs will cause the rockers to fatigue sooner. So, I ordered the Steel Billet and yes, it will cost me a pretty penny.

Thanks Andrew for the reply.

[btmatt]

Hmmm. I would think that a rocker cycle is a rocker cycle is a rocker cycle irregardless of the RPM. That being said, we have used T&D on drag cars before with good success. But, they are definitely a wear item and should be replaced after a set cycle based upon cam, spring etc. due to work hardening, stress, etc.

If you find a steel product that will provide an acceptable moment of inertia that allows you to maintain valve control to your desired RPM, you will definitely have less headaches.

[nokones]

3 weeks ago, T&D Machine told me that it will take 6-8 weeks to build the Billet Steel Shaft Rocker Assemblies. I said oh well, here is an opportunity to run my bone stock Grand Sport until I get my rockers built and shipped. To my surprise, they showed up yesterday by UPS. They will be installed today and now I'll get to run the Enduro Autocross at Thunder Hill next weekend. OUTSTANDING

[CliffsBlueCamaro]

Awesome!
Under promise, and over-deliver - that's a smart company.