Roller Rockers in Stock

[Rory McNeil]

Steve, i can`t speak for the MoPar guys, but every production Ford FE (332,352 thur the 427 & 428`s), came from the factory with iron rocker arms. There was never a stamped steel rocker arm made for the FE Ford. There were 2 different versions of the FE iron rocker arms, the hyd. lifter engines had non adjustable rocker arms, the solid lifter versions had adjusting screws. The non adj. rockers were rated at 1.73 ratio, the adjustables were rated at 1.76, but like most factory rocker arms,advertised vs real world ratios don`t usually jive. The adjustable rockers I checked were normally under 1.73.
The same situation with the SB Ford stamped steel rockers, my 5.0 Mustang rockers normally test at 1.53-1.54, Fords spec is 1.60. I would imagine that the GM and MoPar OE rockers normally don`t compare favorably with the factory specs either.

[Steve Calabro]

Rory, Thanks for the info. The rocker ratio is not the problem. You can make it up with cam lobe, pushrod length, and as a Ford guy by shimming the stand. You can also put the adjustable rocker on a non adjustable (hydraulic) non factory non stock valve train! All i'm saying is that many combos can use non OEM valve train parts that are more reliable so why not roller rockers for the GM guys or evereyone if they stop breakage and major expense if they do?

Steve

[Chris Hill]

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.

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.

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.

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.

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,

[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.

[Todd Hoven]

A good friend of mine came up with this so I figured I would share it with you guys. If guys are pushing for Roller rockers, fine. Let's limit valve spring pressure, say to 150 on the seat. This would limit the RPM and no body would need roller rockers. The second they give us roller rockers we will start seeing 9000 RPM bigblocks, with 350 PSI on the seat if guys arent doing that allready. What happens then? When the engines start coming apart, are these guys going to start pushing for a light bottom end so they can turn the RPM with out having to risk running over the crankshaft about the 1000 ft mark. How fast will cars go then AA car will run the low nines and then we will need rules for people to feel safe, and all that nonsense can start up again. This is a bad idea and will add up to another nail in the coffin for stock. Lets just leave things alone and race for a few years.

[SSDiv6]

Originally Posted by Todd Hoven

A good friend of mine came up with this so I figured I would share it with you guys. If guys are pushing for Roller rockers, fine. Let's limit valve spring pressure, say to 150 on the seat. This would limit the RPM and no body would need roller rockers. The second they give us roller rockers we will start seeing 9000 RPM bigblocks, with 350 PSI on the seat if guys arent doing that allready. What happens then? When the engines start coming apart, are these guys going to start pushing for a light bottom end so they can turn the RPM with out having to risk running over the crankshaft about the 1000 ft mark. How fast will cars go then AA car will run the low nines and then we will need rules for people to feel safe, and all that nonsense can start up again. This is a bad idea and will add up to another nail in the coffin for stock. Lets just leave things alone and race for a few years.

Todd, many of the stockers are running high pressures with Schubecks and many engines are already turning high RPM's. How are you going to check for springs pressures on every car at every race? Don't you realize that what you are proposing would create more engine failures? Do you know the definition of "valve float" and its consequences?

[Jeff Lee]

Chris,
In E/Stock I originally had Don Little build my first set of heads and provide me with a camshaft. Those rockers also failed. In previous posts on this subject, back about a year or so ago, Woodro Josey cam out and stated as an engine builder he was all for roller rockers in Stock. That's two names on your list you probably didn't consult. My camshafts were always the work of Chris Padget at this point and we went thru at least a half-dozn different grinds. One was even a Bullet grind. Most made the car faster and the trend was definetly more aggressive lobes. All experienced rocker failure.

By the time I was in D/S my car was decidedly faster. By now I was having Bud Yancer build my engines. He is an accomplished Comp engine builder and is recognized in P/S ranks and was formerly building engines for a top-ten team in the '90's after finding an un-heard of 25HP for the team in his first year. Bud not only designs his own cams (based not only on his experience but a $25K program that is a few levels above the Cam Doctor program), but he builds his own cams on his own cam grinding equipment. I don't think anybody in your list can lay claim to that level of skill.

And by the time we left D/S and moved into SS/H, I had the fastest D/S car in the country with official times of 10.55 @ 125. So I would say that in the end we wern't a bunch of idiots struggling with an engine. And spring pressures, surely no where close to OEM were as high as 225#'s on the seat and 425#'s open (.457" lift). Those rates actually helped breakage as indicated by SSDiv6 to Todd H. But still, breakage occured and it was almost a requirement to check lash every other pass. Not race, pass! And yes, Chris, I would agree with you that is a result of excessive ramps but then again the results of our efforts was a fast car.

Rockers tried over the years were OEM used, OEM NOS, Crane Nitro for SBC, OEM, cryogenic, OEM coated. Rocker balls were 3/8" and 7/16" both OEM and aftermarket, grooved and non-grooved. Oh yea, also tried PVS rocker arm system with powdered metal rockers and balls.

I have about 5 sets of various length pushrods due to one grind over the other.

Lifters tried over the years ranged from Comp Cams race hydraulics to Shermans, composite body Schubecks, composite base / steel body Schubecks and even chilled-iron flat tappet converted to "hydraulic". Cams ran from standard cast to billet steel. Are you totalling the price tag in your head? Yea, it wasn't for lack of funds either. And in the end, we pretty much had a better system but still had to stay on top of lash every other run and still had failure. Speaking of failure, my one and only final round in a National event was paved by one single in the quarter-final. Guess what? A rocker arm broke! Good thing it was a bye-run. So think about that. Had I had an opponent and lost due to breakage, how much would that have cost me?

But that's my point. Given all the altered, non-OEM parts allowed by NHRA to the valvetrain, why should anybody have to go down this path of broken engines and light-weight wallets? Either go back to 1965 valve-train rules or finish the job. The only part of the valve-train that is not stock is the rockers. And you know as well as I do, NHRA will not rescend the rules in place today.

Todd,
396/375 engines in Stock exceed 8,000 RPM today. They have the same technology I had in my engine's valve-train. Additionally they have 9/16" studs and 8.0L rockers. That's about a $750.00 upgrade above what I ran.

So I want to ask the Small-block Chevy and SB Ford racers something. Since the LT4 and 302 Cobra engines used factory roller rockers as OEM installed, why hasn't somebody from each camp petitioned for allowance of their use on the other SBC and SBF's? The precedant is there and that is all NHRA needs. That's how the beehive springs came into play (LT4) and larger pushrods and guideplates (SBC rail-type rockers). That's also how SB and BB Mopars with stamped rockers got ductile-iron Isky rockers (273 SBM and 426MW BB Mopar). Wake up!

[Todd Hoven]

Sure, I know the definition of Valve float. When the valvetrain cant keep up with the valve opening and closing the parts kind disconnect and hammer against each other causing impact damage and so on. That being said, You can design camshaft lobes and be easy on parts thus reducing valve train failure. Right now it's a risk and reward, guys want to run big agressive lobes and make big power. The reward : an engine and revs high and makes big power throught the range, resulting in Fast ET's, good quailfying stats. The Risk: unstable valvetrain a chance for catastrophic failure. The racer will have to decide whats is more important, Running fast or running safe. You can have a guy in Tech have an on the car valve spring checker. He he pulls it on the car and the pressure is way over he's out.Guys back in the 70's and 80's had no Shubecks, or big valve springs. They survived and raced. What happens when engines are running super high RPM and they start coming apart, will guys start lobbying for lightend bottom ends because it's a safety factor??? I'm sure of it. This is not an easy game, guys been playing for along time within the rules and being succesful. SOME of the racers of today don't want to make what they have works, so they Bitch and cry for rule changes because they ran out of talent, money and the will to make due with whats available. This is what stock is about.





Todd, many of the stockers are running high pressures with Schubecks and many engines are already turning high RPM's. How are you going to check for springs pressures on every car at every race? Don't you realize that what you are proposing would create more engine failures? Do you know the definition of "valve float" and its consequences?

[SSDiv6]

Originally Posted by Todd Hoven

Sure, I know the definition of Valve float. When the valvetrain cant keep up with the valve opening and closing the parts kind disconnect and hammer against each other causing impact damage and so on. That being said, You can design camshaft lobes and be easy on parts thus reducing valve train failure. Right now it's a risk and reward, guys want to run big agressive lobes and make big power.

Oh boy...you have a lot to learn about camshaft design; agressive lobes are not required to make lots of power. Not every stocker cam grind works the same because there are lots of factors that need to be taken in consideration.

The reward : an engine and revs high and makes big power throught the range, resulting in Fast ET's, good quailfying stats.

Another falacy...there are lots of engines that do not need to be twisted to higher RPM's to run fast because they are limited on its design. Ask anyone that races a Buick engine or a late model Mustang 302 F.I....they cannot spin their engines due to breathing limitations.

You can have a guy in Tech have an on the car valve spring checker. He he pulls it on the car and the pressure is way over he's out.

Keep dreaming.

Guys back in the 70's and 80's had no Shubecks, or big valve springs. They survived and raced.

I do not know how old you are, but I have been doing this for a very long time. In the early days, even with the spring limitations and old cam specs, you still had failures.

What happens when engines are running super high RPM and they start coming apart, will guys start lobbying for lightend bottom ends because it's a safety factor???

Why do you think NHRA put weight limits on the reciprocating mass?

I'm sure of it. This is not an easy game, guys been playing for along time within the rules and being succesful.

Like I said, I have been in this sport for over 35 years and playing for a long time and have seen the evolution of the rules. When there is a rule change, you adapt to be competitive.

SOME of the racers of today don't want to make what they have works, so they Bitch and cry for rule changes because they ran out of talent, money and the will to make due with whats available. This is what stock is about.

Your statement is sort of an insult to many of the well respected engine builder in Class racing that are busting their asses. They have expereinced rocker arm failures too like everybody else. Just do a search, read the posts and edify yourself.

In a nutshell, if you read many of my earlier posts, I have made it VERY CLEAR, that the problem with stamped rocker arms is the QUALITY of the product. We live in a global world were parts manufacturers are outsourcing parts overseas. The process is not the same as in the early days, they are producing a lower quality product, with cheaper labor and processes. By the way, I know of two particular cars that are running a cam grind that was designed before the camshaft rule change and they are also breaking rocker arms too.

[Dave Noll]

...