Roller Rockers in Stock

[Dwight Southerland]

In regards to running roller lifters in a non-roller lifter engine, I believe you would run into difficulty since the lifter type is part of the tech specs. Rocker arm type, however, is not, only the ratio.

[Jeff Lee]

Todd,
One thing I never mentioned. My Stocker AMX was shifted at only 6500 RP, launch @ 5800 RPM. I wouldn't conider that excessively high for a 4-speed Stocker. Though maybe that's high for a Pontiac...

Regarding breakage, I not only experienced the pushrod through the rocker cup, I also experienced the rocker arm lifting at the folcrum numerous times. How could that occur? Just as SSDiv6 has stated, it's from inferior production techniques. Simply stamping out a rocker arm on a cold plate of steel stretches the metal, especially in the area where the rocker ball situates. Since this area is the receipient of the most stretching, this is the weak area. I'm not an engineer but I would suspect any area stretched into a ball or semi-ball shape would be weak. Thus the breakage at the (1/2 round) push rod cup and the rocker ball folcrum area. What I witnesed each time the folcrum area failed was (typically) four stress cracks that originated from the very bottom which traversed vertically. In essence, the rocker arm was attempting to pull itself away from the rocker ball. The rocker arm would mushroom out in this area never leaving parts behind, they would just flare outwards. I always considered myself very lucky that a broken rocker never caused other engine damage. Broken lifters (Schubecks) are another story.

A local friend of mine by the name of Ron Smith still owns the '72 Duster 340 he bought brand new with the specific purpose of racing in Stock (H/S). That's a hydraulic cam, low-compression 340 T-Quad engine. Back in 1972 he was breaking factory rockers. Only now will he addmitt to "cheating" by running the HD Direct-Connection stamped steel rockers (which I believe were the receipient of a heat treat process or maybe just the A+ parts off the assembly line; before the allowance of Isky ductile-iron adjustable rockers in Stock to non-OEM equipped MOPAR small blocks). Only then did the breakage trickle down. So that's at least one racer I can name who can valididate problems with a shaft-mounted system before the advent of really radical spring pressures and cam lobes. I have spoken to others but I can't remember enough of the specifics to bother with mentioning them as sources. So again, this is not a new phenomenom (sp?).
As SSDiv6 keeps trying to drive home. this is primarily a problem with inferior parts.
Thanks,
Jeff Lee

[Jeff Lee]

The following is from a post on the AMC Forum. It is regarding cylinder head gaskets and I chimed in about the SCE "ICS Titan" product line. It is a MLS product with an integeral O-ring surrounding the cylinder.
I thought it interesting enought to post it here on this subject. Specifically, I wanted to show how a quality minded manufacturer see's what happens to the end user's once the bean counters step in. I believe these comments apply specifically to the discussion of stamped rocker arms.

Ralfy,
I forwarded this link to Ryan Hunter, President of SCE Gaskets. I have a limited engagement with SCE as I was the one who asked for this product (AMC) and received the first batch when they came from engineering. I asked Mr. Hunter to read the link and specifically your comments.
I received an immediate response which reads:

Jeff,
I read the thread and I want to thank you for your comments. Unsolicited endorsements from actual users at your level of competition can’t be bought, whereas paying for space in a magazine can be done by any company regardless of the quality of their part and too often the consuming public believes the propaganda. SCE has been around long enough to see several cycles of what was described in the posts by users of other head gaskets; raw material costs go up, the bean counters require better profit performance, so cheaper raw materials are sourced and the public is unaware that what used to be the best is now equivalent to a cheap import. As a racer you know how difficult it can be to trace down hidden problems; you know something is different, but what changed? Cost cutting at the expense of quality and performance hurts the consuming public, it’s the old bait and switch.
The best that true performance manufacturers can hope for is to have users like you tell about their experience and help get others back on the trail. To be sure, our ICS head gaskets are very expensive; not because “it’s patented and we can get away with it” rather, they are very pricey to manufacture. Still, I could not do business with a clear conscience if I wasn’t also sure that the buyer is getting better value, as the hackneyed saying goes “the sting of poor quality will surely outlast the joy of a low price”. Thanks again,
Ryan Hunter
President
SCE Gaskets, Inc.
rhunter@scegaskets.com
661-728-9200

[Run to Rund]

With ported heads, etc. SS today is basically MP of the 1970s. Stock is close to the old SS. Why not allow any cam, maybe restricting lift, so you can use roller lifters at half the cost of Schubecks and several times the durability? Roller rockers, of course. Then look back to 1973-1975 and create a real Stock eliminator class again. We have stockers today with very little stock feel and texture, so to speak. Aftermarket heads, rods, etc. wow.

[Chris Hill]

Sorry I've taken a long time to reply, but here's what the engineering calc say:

1. If you take all the worst case conditions for a valvetrain force WITHOUT IMPACT occuring and current Stock Eliminator valve spring forces, the peak load is approximatly 1,000 lbs at the valve.
2. Per a test by David Vizard in his book, Small block Chevy Valvetrains, a stock Small block Chevy rocker arm breaks at 3,000 lbs.
3. The safety factor on the rocker is 3:1. In lay terms, the the rocker arm is 3 times as strong as it needs to be and will last a VERY long time if impact does not occur.

You can try to beat around the bush all you want, but a rocker with that much safety factor will not fail if the camshaft is designed correctly for engine speed.

Why am I very confident in my statements? Because I have run or supervised valvetrain performance testing and durability testing for 1000+ hours of spintron time.

A higher quality rocker will help the situation some, but it's like putting a band aid on something that needs stitches.

Better materials and heat treatment DO NOT replace correct design and engineering of the camshaft events.

[Jeff Lee]

Originally Posted by Chris Hill

Sorry I've taken a long time to reply, but here's what the engineering calc say:

1. If you take all the worst case conditions for a valvetrain force WITHOUT IMPACT occuring and current Stock Eliminator valve spring forces, the peak load is approximatly 1,000 lbs at the valve.
2. Per a test by David Vizard in his book, Small block Chevy Valvetrains, a stock Small block Chevy rocker arm breaks at 3,000 lbs.
3. The safety factor on the rocker is 3:1. In lay terms, the the rocker arm is 3 times as strong as it needs to be and will last a VERY long time if impact does not occur.

You can try to beat around the bush all you want, but a rocker with that much safety factor will not fail if the camshaft is designed correctly for engine speed.

Why am I very confident in my statements? Because I have run or supervised valvetrain performance testing and durability testing for 1000+ hours of spintron time.

A higher quality rocker will help the situation some, but it's like putting a band aid on something that needs stitches.

Better materials and heat treatment DO NOT replace correct design and engineering of the camshaft events.

Well Chris a blind man could see you were going to end up with these conclusions! And that's why I made the first post
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.
When you asked for all the weights of the SBC valve-train, I immediately asked a few questions because as I stated, The devil's in the details". To refresh:

How does the "modern" cold stamping process, inferior metalurgy, and subsequent poor quality product figure into your calculations?

Which rocker? OEM non-rail, OEM rail type, PVS (Precesion valve systems), Crane Nitro?

What size valvespring are you looking for? 1.250"? Larger is possible and still comply with the rules. Behive should be considerably different in weight.

What size retainer are you looking for? Behive should be considerably different in weight.

Stock steel retainers (what valve spring size?) or chromoly or maybe the new machined tool steel (lighter than chromeoly, almost as light as titanium)?

Solid lifter, hydraulic or hydraulic roller? What lifter, standard replacement, Schubeck with puck or Schubeck with all composite body? Tool steel lifter body?

What pushrod? 5/16" 3/8" 7/16", maybe 1/2" per the new rules? Chromoly or standard?
I haven't seen the new rule so maybe by now composite pushrods are legal (just like composite body Schubecks are legal).

What valves? Hollow stem or standard? Hollow stem of course would not be legal. At least Inot that I'm aware of.

The devils in the details!

I note you did not address these concerns. If your discussing the science of the issue, I would think it would be imperative these issues are addressed.

On your last post you stated:

A higher quality rocker will help the situation some, but it's like putting a band aid on something that needs stitches.

Great observation. A higher quality rocker will help the situation. Absolutely. But is it a band-aide when you substitute a "yester year" SBC stamped rocker for "today's" inferior product? If "yester Year" parts are long gone, then what? A suitable substitute is needed.
And I'm sure with over a 1000 hours on your spin-tron you recorded the rockwell hardness of all the stamped rocker arms you used. Right? What other methods were used to insure the quality of the parts you tested? What percentage of time is a spin-tron in use with stamped rocker arms and no aftermarket support systems (stud girdle)?

Chris, I admire you for taking the initiative and if proper testing was noted I might be swayed. But your own evidence seems to support the fact that higher quality rockers are needed. The issue is where do we get the higher quality rockers?

I might be even more swayed if your family took the non-OEM rockers made of ductile iron instead of stamped steel of the 440-6 'Cuda and replaced them with what the factory placed on the engine as it rolled down the assmbly line. I think then you might be crying a different tune. Or is this a method of protecting an unfair advantage???

[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.