having the correct ratio on a rocker is an advantage, and so is stronger construction. the function of the roller tip is in question. the extra money invested in a rocker that also has a roller trunion has an advantage over the conventional style with a steel ball rubbing the actual rocker. full roller rockers are available at pretty reasonable prices now days. a lot of roller rockers will fit under the stock cover with little or no work. i wasn't trying to insult anyone. but all things considered a full roller rocker is a better way to go.

 

Did you read this on the internet?

 

I agree completly, but think the roller tip are a little better than the stock rocker.

 

HaHa! actually read it in a magazine where they interviewed one of engineers responsible for designing the LS3. It was a specific question, because everyone assumed that high performance engines need roller tip rockers.

 

I can 'grasp' what the GM engineers 'say' on their thoughts on a roller tip versus stamped rocker arm. Knowing that stamped rocker arms have been used for decades with basically great success...why change.

But...for the life of me...I will not buy into they are both the same. By the design alone...they are different....and the rolling wheel on a roller rocker arm is rolling back and forth....while the stamped rocker arm is sliding across it...and if you take into account the distance....and oil lubricating this area.....YEAH....MAYBE there is not a noticeable difference....but I am still feel a rolling wheel ...rocking back and forth is not adding any scrubbing to the tip of the valve to itself....versus that of a stamped steel rocker arm....which I have actually seen wear on when I remove them.

AS for the roller rocker breaking apart ....launching parts in your head....I knew it happened a long time ago...but I have not heard of it recently...so I think the manufacturers figured out how to make them so they do not blow apart.

There is also a lot to be said about the simplicity of a stamped rocker arm. But I have replaced many that have broken in half also.

Honestly ...I do not care either way. It is up to what the owner wants to do. But...logically...at least in my mind...it seems that a roller tip provides 'something beneficial' that the stamped arm does not....so why not go with it....especially if you are dealing with an engine with high valve spring pressures.

DUB

 

I think whether the roller tip is rolling or not is going to be a function of the spring pressure used and the RPM of the motor.
As the spring pressures rise then the force applied to the valve tip is going to rise. This additional friction is going to make the roller tip more likely to roll as designed. Not much if geometry is correct but a little.

Then as RPM rises and there is less time to overcome the inertia of the roller on the tip of the valve it may and probably does begin to slide. At what RPM it does this is again going to be a function of spring pressure. Less spring pressure will slide sooner.
It will also be a function of the mass of the roller itself. Larger roller, more inertial mass to overcome. It appears that pretty much rollers are the same size.
The friction reduction capability of the oil will come into play as well, but keeping that a constant, spring pressure and RPM will be your main controlling factors.

 

I agree, a roller sounds better, IF it is rolling.
So, the question is, do they roll? Who knows. I have seen videos of rollers just sliding across the valve tip. Happen all the time? Who knows. GM not using them on a lot of their engines--and I'm not talking about LS7's etc., but more of the base engines that would be more comparable with the engines in our C3's have, says a lot to me.
There is a lot of internet "known truths" and old school thinking that everyone "knows" is true, such as you need forged pistons (again, the 430 hp, 10.7/1 compression ratio LS3 uses cast pistons). But that's another whole issue. A lot of parts are not needed, over kill, or in the case of full on race parts, not needed and may not work well or endure long on a stock 300 hp small block.
So, do you NEED roller tip rockers? No, but they MAY help, and if it makes you feel better, go ahead. I don't see a down side with a quality product except for price if you're on a budget.
I also get a kick about someone saying that the stamped rockers have to go because they are notorious for ratio variations. IF true, what about the stamped rockers from Comp, Crane, etc. that are 30%-50% cheaper than their roller tip cousins?

 

The only benefit to stock rocker is that the margin for error on the geometry is slightly larger.

 

Let try this one more time…Stamped steel rockers especially Gen 1 small block rockers had very poor production tolerances resulting in variable rocker arm ratios….Aftermarket stamped steel, not roller tipped rockers, will have more accurate rocker arm ratios since the production tolerances are tighter.

 

So, after market stamped non rollers are OK? Disregard items 1&2?
#3 A smaller surface area roller tip SLIDING over a valve is more desirable than a larger area non roller tip rocker SLIDING over a valve?
Seems that Katech Racing doesn't agree with you.
https://www.corvetteforum.com/forums...cker-arms.html
But, like I said, a 500+ hp racing engine really isn't relevant here.

 

Aftermarket roller tipped rockers, not full roller rockers do have a slight advantage over stock rockers. Again, slight advantage.

1: The ratio, 1.5 or 1.6 to 1 is a true ratio over factory stamped steel rocker arms that can have ratios as low as 1.3 to 1.

2: The rocker arm slot at the rocker stud usually is longer and allows for more lift from aftermarket cams.

3: The steel is of better quality most of the time over OEM, and the pivot ball is grooved for better oiling. But, we are talking a crude metal pivot against a metal fulcrum that for some damn reason will last for 100's of thousands of miles.

All divisions of GM along with Ford and others used this style unless they were shaft style rockers.

4: The oil hole in the rocker is properly located, directing oil towards the pivot instead of in the sky. Those of you that still set valve lash in the antiquated way with the engine running will immediately notice the oil is directed in the right direction. That was the way I adjusted valve lash until I was taught the right way to do it with the engine off.

5: The roller tip bearings never roll 360°, they just rotate back and forth a few degrees. This is still better than dragging across the valve stem face as a stock rocker does.

The major friction point is at the pivot ball, where a needle bearing true roller is superior in design. Until it fails and the little bearing needles find there way to the oil pump and lock the pump up. Screened block or not.

So, roller tip rockers from a geometry and reliability point are better than stock rockers, but definitely not a "True" roller rocker arm.

 

You forgot
#6 the extra weight, oh wait thats not an advantage.

 

 

Actually, the Comp Cams are 1.52:1 offering a slight advantage over the stock advertised 1.5:1.

The difference? With the 327/350 cam, the lift is increased from an advertised 0.447" to 0.453"

Actually, there is still "dragging" at the tip. While the roller may roll across the valve stem, the inside of the roller is dragging around the trunnion if it is stationary within the rocker.

If the trunnion floats free so that it can also rotate within the roller, than it is dragging where it meets the rocker. So without some intermittant bearing (e.g., needle bearing), there has to be a certain amount of sliding somewhere.

 

I've always preferred a fully formed roller rocker for cam profiles that exceed base HP output, if only for the strength offered at rpms higher than 6 grand. Of course, they usually warrant a taller valve cover for clearance so they are not for everyone.




Roller tipped rockers are a great solution for a myriad of applications and I would use them too, as needed.