Roller Rockers in Stock

[Chris Hill]

Jeff said:

Chris, I admire you for taking the initiative and if proper testing was noted I might be swayed...

That's the thing, I have tested this before. We had another valvetrain that was failing. It would be fine for a couple of hours on the test stand, then it would fail. The valve lift curve showed good seating velocity and no spikes in the velocity and thus acceleration. To double check our data, we bolted an accelometer to the intake valve and retested with new hardware. During the closing of the intake valve, an impact was occuring and the accelometer was showing VERY LARGE accelerations and thus forces. Any safety factor that we designed into the part was then moot. The material on the parts was Stainless steel 316, the good stuff. We even tried making parts out of 52100 (bearing race steel, rockwell hardness of 58-62c scale). The parts still broke with bearing steel. Then we changed the design of our valvetrain to lessen the impact loads, we could use the original Stainless steel material. The issue was not the material of the part or heat treatment, it was just a bad design.


Jeff also stated:

And not trying to get personal, but it's obvious you have failed to understand the parts offered today are inferior to yesterday. Done, end of subject.

And to prove a point, I've used rockerarms purchased at Autozone in 2003, ran them in my v-6 small block Chevy upto 7,200 rpm with out failures. I understand the standard Autozone rocker is not as good as 1967 Z-28 rockerarms. I understand the issue at hand very well and make sure my stuff works in the operating range it was DESIGNED for.

Impact in the valvetrain is breaking your rockerarms, reguardless of the material used for the rocker. If you keep having breakage, figure out what is causing the impact.

The solution is don't run as much rpm, it is that simple.

[Jim Bailey]

We've been Cryogenic Processing in combo with Rem Finishing Rocker Arms for 3 years now. We've yet to have a failure of a stamped steel rocker arm, as well as "all" others brands. The cost is $5.00 each. Many of the smallblocks see 7800 every run. What's the problem?

[Charley Downing]

I have been using jim's products for over two years in all our race cars ( sb olds and sb chevy) it is by far the best was to go NHRA stock racing with out breaking parts,

[Jeff Lee]

I can't imagine that a 6500 RPM stocker is considered "high" RPM. But high or not, it was with larger or more radical camshaft design that the car responded with quicker ET's and faster MPH's, with the limitation on upper RPM being placed on the small Autolite carb I ran. Now I guess if I were on the outside of the conversation listening in, I would maybe say "so Jeff Lee, I'l bet you never got that AMC 390 to run very well because obviously you don't have a handle on the valve train issues". Well, the best times were 10.500 @ 125.01 in D/S in what was "killer" air; in Arizona (which never see's air like the sea coast tracks). But typical would be a 10.62 @ 124.7 @ NHRA events.
So I guess that would lead me to "so your saying I need to lower the RPM and ET/MPH to save the parts"? Well tried that. All I can say is it went slower. And I guess for me that's a bitter pill to swallow.
Now I also have spoken to Vic Guillimo (I know, incorrect spelling). His 429 Ford, which is equally as fast but in D/SA, tells me he breaks rockers more frequently than even I did. Clark Holyrod came up with a substantially larger system which he markets to reduce or eliminate breakage. Aparently he, and his (many) customers along with Vic & I haven't been able to come up with the camshaft that will work in Stock that gives a 3-1 safety margin on rocker safety. Maybe the answer is a "pure Stock" cam?
Now if I had to guess at the one thing these racers mentioned above have in common is high compression ratio's on their NHRA blue-printed engines (429/396-375/427-425, etc.). Maybe that's part of the issue as well, I don't know. I just know they have issues, not just stupid old Jeff Lee.

[Jeff Lee]

Furthermore...


Chris Hill stated:
"The parts still broke with bearing steel. Then we changed the design of our valvetrain to lessen the impact loads, we could use the original Stainless steel material. The issue was not the material of the part or heat treatment, it was just a bad design".

Jeff ask's:
So you had failure with stainless rockers, developed a whizz-bang cryptonite rocker to no avail, then fixed the cam lobe and then the original stainless rocker stopped failing. Is this correct? So a better cam lobe solved the problem and therefore your confident that a standard Speed-Pro SBC stamped rocker available from AutoZone will get the job done on the lobe you and your crew developed under competition useage (burnouts. various loads, possible missed shifts, etc.)
So my big question is, what type of cam lobe are you testing against? Is this a NHRA Stocker lobe with approximately .450" lift (which I'm guessing may be an average) with duration and ramp designs that will allow the engine to be competitive? Or are you talking about a bracket-style, maybe even street / strip style cam lobe that is much less aggressive than the Stocker lobe?