Mancini has their brand rocker they claim are made by Harland but much cheaper.
Rocker arm recommendations?
- Thread starter dukeboy440
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I've tested just about every Mopar big block rocker arm that has ever been sold. Here are a few on one of my later tests: Trying to Find Extra Power Through Rocker-Arm Testing
Bighead440
Well-Known Member
I like them because they are bushed, but have the Harland body and shafts.
Correct, which is why they are cheaper. I agree, dont totally trust needle bearings and if you dont need them why risk it.
Bushed? Are you sure about that? I ask because the ones I have purchased (and I like them) have the aluminum body running on the rocker shaft, as do the Hughe's rockers.
Bighead440
Well-Known Member
I ran Cranes way back in the 80s with aluminum riding on the shaft, but the Mancini rockers looked like regular Harland Sharp rockers with oilite bronze bushings instead of caged needle bearings. I don't own them, just saw photos and an analysis of them when they came out.
No bushings if I remember correctly. The aluminum body rides on the shaft. I have some RB ones here, let me take a look.
Edit: nope, no bushing.
Edit: nope, no bushing.
Bighead440
Well-Known Member
I looked at a post on MoParts that had a picture indicating just that. I must have dreamed or envisioned them with the bronze bushings. I actually have a set of Buick rockers offered by Kenne Bell back in the '80s-90s that are red anodized with bronze bushings for a 455 that may add to my dementia on the subject. LOL
autoxcuda
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I also have a set of comp SB rockers for 10 years now. But less than .525” lift on solid flat tappet.
Also 10 years ago I got the Comp cam and lifters
BUT a few months ago my buddy had TWO XE268 comp cam and lifters go bad on the run stand immediately. 3 weeks apart.
then he put a 20 year old new in box Mopar Performance set of cam and lifters in.... NO PROBLEMS WHATSOEVER.
something has changed over there at Comp. Maybe just a cam thing... but makes me leery of all Comp stuff.
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We use the Comp rocker arms all the time and haven't seen any issues. They are about the only rocker arm that I trust to last on a street car with a solid roller cam. For drag racing the aluminum arms work fine, especially if the engine is maintained by a mechanic who actually takes the valve covers off and inspects things once in a while.
B3,
I totally agree that many brands of rockers leave much to be desired.....
In post #8, I was referring to this statement in Part 2 of your tech:
'It is now[ the geometric point of rotation ] at the centre of the roller axle & maintains that point throughout the whole lift range, which means the ratio stays constant as well'.
This is simply incorrect. The ratio on the valve side is from the centre of the fulcrum to the point of contact of the roller on the valve tip. This does not stay constant, it changes through the lift cycle.
Smokey Yunick says it well:
'As the point of contact of contact moves outboard, the effective ratio length of the valve end of the is increased. .......as the valve is being returned to the seat ,the point of contact is moving inboard & the effective length of the lever arm is decreasing.'
D. Vizard did extensive testing on various rocker arms, results published in his BB Chev book. He tested initial ratio, TDC ratio & overall ratio. Large variations with some.
I totally agree that many brands of rockers leave much to be desired.....
In post #8, I was referring to this statement in Part 2 of your tech:
'It is now[ the geometric point of rotation ] at the centre of the roller axle & maintains that point throughout the whole lift range, which means the ratio stays constant as well'.
This is simply incorrect. The ratio on the valve side is from the centre of the fulcrum to the point of contact of the roller on the valve tip. This does not stay constant, it changes through the lift cycle.
Smokey Yunick says it well:
'As the point of contact of contact moves outboard, the effective ratio length of the valve end of the is increased. .......as the valve is being returned to the seat ,the point of contact is moving inboard & the effective length of the lever arm is decreasing.'
D. Vizard did extensive testing on various rocker arms, results published in his BB Chev book. He tested initial ratio, TDC ratio & overall ratio. Large variations with some.
famous bob
mopar misfit
THIS IS WHY U STRIVE TO RUN A VERY NARROW/CENTERED CONTACT PATCH BETWEEN THE ROLLER AND VALVE TIP------------JMO
Most, if not all, mass produced Mopar rockers.
I know what you were referring to, and addressed it in my last post. You are referring to shoe type rocker geometry, which is what I explained in paragraph 2 of that tech article. There are many people who try to treat a roller rocker as having the same geometry as a shoe rocker, and that is incorrect. They are significantly different.
Again, using shoe rocker geometry on a roller rocker. The point of rotation is at the center of the roller axis, and not at the contact point like a shoe rocker. The effective fulcrum length remains constant.
Also, the ratio is observed on the valve side, not determined. It is determined by the fulcrum length divided by the center to center distance of the fulcrum, and the pivot center of the adjuster to pushrod interface. If the adjuster side of the rocker is not correctly designed, or not set up properly, the input values on the pushrod side will be wrong, and the resulting ratios will not be constant. As the rocker sweeps on the valve side, it also sweeps on the pushrod side, and that affects ratio. If the pushrod side is right (rocker design), and the fulcrum position is right (stand position), the ratio remains constant
No kidding! How many people realize the complexity of the valvetrain on a canted valve, dual angle lifter application? How many rocker sets for a BB Chevy have a different rocker design for the intake vs the exhaust? If they want it to be right, that is entirely necessary. But, that drives up cost, increases overhead, increases confusion among those who don't understand the complexity, and thereby reduces sales. Keep it simple and make more money. Most people only check ratio at full lift, so as long as it's close there, it's a winner. right?
I had this conversation yesterday with one of my rocker vendors, and he said one of their sponsored BB Chevy race cars ran their rockers with 850# of open pressure for multiple seasons without issue. They built a new motor with different heads that had a modified valve angle, and using the same valvetrain components, now they can't keep pushrods in the motor and it is breaking rockers. In reality, that change in valve angle required a different rocker design and set up.
That's why I have T&D make custom rockers to my spec for many Mopar applications. I don't do it because I'm bored and need something to occupy my time. On the contrary, I wish I had more time. I don't advertise these rockers, yet I have been selling quite a few of late, because guys who want everything right find out about them and call. I even have some running down under in Australian Pro Stock.
I've also done some of my own testing and research into rocker design and issues with ratio. Check out these "Mopar" rockers that leave a lot to be desired. You can see where the ratios did not remain constant because of the poor adjuster position. This is just a sample of the work we have done to try to build a better mouse trap. Btw, this was after converting to a cup adjuster to increase efficiency, but it was still off a bunch.
In the end, you are welcome to disagree with me all you want. I have no problem with debate, and think it is valuable to society. I have been able to make my case, and you are welcome to still disagree. But, it was never really about that. My response was about the advice to take everything I say with a grain of salt because you disagree with one paragraph, or even a few sentences in a tech article. To that, I will defend myself, and my reputation for giving good advice. Now, I must get back to work.
beanhead
Well-Known Member
B3,
[1] No argument from me that rocker ratio & design is a dog's breakfast.
[2] Vizard's testing had nothing to do with the fact that the engine he used had canted valves. What his test wanted to show, & it did, was how the variation in different brands of rocker designs changed the ratio events. Things such as if the pushrod cup was higher or lower, how much if any did it affect overall ratio. Another example is the Crane 'fast lift' rockers; they achieved their early high lift by lowering the p'rod seat on the rocker.
[3] The rocker ratio comprises two components, the p'rod side & the valve side. If you are saying the ratio on the valve side of a roller tip rocker remains constant, then this is simply incorrect & Smokey explained it very well.
[4] In your above post you say a shoe type rocker has a different ratio on the valve side compared to a roller rocker. If the shoe on the shoe rocker has the same radius as the roller on a roller tip radius, then their ratios [ on the valve side ] would be the same.
[1] No argument from me that rocker ratio & design is a dog's breakfast.
[2] Vizard's testing had nothing to do with the fact that the engine he used had canted valves. What his test wanted to show, & it did, was how the variation in different brands of rocker designs changed the ratio events. Things such as if the pushrod cup was higher or lower, how much if any did it affect overall ratio. Another example is the Crane 'fast lift' rockers; they achieved their early high lift by lowering the p'rod seat on the rocker.
[3] The rocker ratio comprises two components, the p'rod side & the valve side. If you are saying the ratio on the valve side of a roller tip rocker remains constant, then this is simply incorrect & Smokey explained it very well.
[4] In your above post you say a shoe type rocker has a different ratio on the valve side compared to a roller rocker. If the shoe on the shoe rocker has the same radius as the roller on a roller tip radius, then their ratios [ on the valve side ] would be the same.
In reference to;
[1] Wait a minute! You agree with me on something! How is that possible if anything I say is questionable? I disagree with a lot of people on certain things, including Smokey Yunick and David Vizard, but I don't assume they don't know anything at all.
[2] As I have been saying all along, if the rocker is not designed and set up properly, you will not get an accurate transfer of cam lobe information to the valve. Obviously, Vizard was working with a bunch of improperly designed rockers. After all, if they were right, they would have all been the same. The rocker can be manipulated to do things the cam lobe was not designed to do, and that usually doesn't work out too well.
[3] What is this "ratio on the valve side"? Ratio is not dependent on the valve side only. You and Smokey say I am incorrect. Well, you and the spirits summon ole Smokey from the afterlife, and make your argument with someone who has a much higher pay grade than I do. That would be the author of natural law, of which mathematics falls under. Mankind didn't invent math, they simply discovered it. You know, like gravity and electricity.
For your benefit, and others, I have drafted a simple fulcrum, which is all a rocker arm is. The only difference is variations for a specific application.
As you can see, a simple 1.5 ratio on the perpendicular plane has a fulcrum length of 1.500 inches, and the adjuster centerline to fulcrum is 1.000 inch. Now, with a 10 degree rotation, both above, and below the perpendicular line, the lengths change to 1.47721 inches on the valve side, and .98481 inch on the pushrod side. What is 1.47721"/.98481"? Well, at this number of decimal places, that comes out to 1.4999949229. Now, would you like to quibble over 5 MILLIONTHS of a point?
For reference, the combined 20 degrees of rotation with this fulcrum example amounts to a .350" cam lobe lift, and a .520" gross valve lift, which is pretty common for a performance street or street/strip cam, so it's easily relatable.
[4] I never said that, because the ratio is not solely on the valve side. I said the geometry is different.
I'm done, and again, I have made my case. I won't continue to beat a dead horse, and this is really hurting my productivity. FWIW, this battle was fought several years ago on Moparts.
To the OP, my apologies for things getting off track. My advice, for what it's worth, is to take Andys advice and go with the Comp steel rockers, or the PRW steel (more ratios). Either way, the shaft position should be relocated to correct valve side geometry, or if you want both sides right, contact me about a custom rocker set.
yellow rose
Overnight Sensation
Don’t apologize for setting the record straight. I know I need to be more educated on this subject so I appreciate all your posts.
Thanks Jim!
I'll say it again, I owe you a debt of gratitude for the encouragement you gave after the beat down. Tim (yellow rose) also. Kinda feeling a Gloria Gaynor moment here. I will survive.
Absolutely! Just give me a shout if you need some rockers. I'm certain you would be happy with them.
B3,
'Ratio is not dependent on the valve side only'. Of course not, never said it was. I said in post #40, point [3] there is the valve side ratio & the p'rod side ratio.
Your drawing above depicts what I was saying [ & Smokey ] about the ratio not being constant on the valve side. You show the figure of 1.477" at max lift as I presume the lever arm length. If you are using that to calculate the ratio [ valve side ] @ max lift, it is incorrect. At max lift, the lever arm, & corresponding ratio, is greater than the nominal 1.500" because the lever arm is measured from the point of contact of the roller on the valve tip to the fulcrum centre. It might be 1.520", as an example.
'Ratio is not dependent on the valve side only'. Of course not, never said it was. I said in post #40, point [3] there is the valve side ratio & the p'rod side ratio.
Your drawing above depicts what I was saying [ & Smokey ] about the ratio not being constant on the valve side. You show the figure of 1.477" at max lift as I presume the lever arm length. If you are using that to calculate the ratio [ valve side ] @ max lift, it is incorrect. At max lift, the lever arm, & corresponding ratio, is greater than the nominal 1.500" because the lever arm is measured from the point of contact of the roller on the valve tip to the fulcrum centre. It might be 1.520", as an example.
There is not a valve side ratio and a pushrod side ratio. Maybe there is a problem with verbiage here, since in OZ you say extractors, and we say headers, Or, like we say intake manifold, and you say inlet manifold. Still, you are trying to quote Smokey Yunick, and he was American, so that shouldn't be an issue.
What you have is a valve side length, which is commonly referred to as "fulcrum length". This length is determined by the rocker manufacturer based on the cylinder head it has to fit, and their perception of how they want it to fit. Then there is the pushrod side length, which is the ratio length. That length is determined by what ratio the manufacturer wants the rocker arm to be. Both sides are part of the equation, but they don't both have their own ratio. That's simply not possible.
Maybe you should reread what Smokey actually said. Here are some excerpts from Power Secrets. Page 87, under the heading Geometry:
Specifically, number 2. What exactly is the axis of the roller, if it isn't the center?
Next, the claim that the rocker keeps moving outward and "lengthening" up to full lift. That's not what Smokey had to say. Read the last two sentences. By the way, the last word that was cut off is "inboard".
And here is the little nugget you have been talking about, which is one of the areas I disagree with Smokey. Maybe he just didn't have a decent rocker to work with, but this is a flaw in theory if I've ever seen one.
The lever does not get longer as the point of contact moves outboard, although I know what he is trying to say. It is just a poor choice of words, in my opinion. The rocker is going through an arc motion which pulls the contact point back at any position other than perpendicular to the valve stem centerline. His reasoning is that the ratio increases because the "lever gets longer". Well, so does the pushrod side when the rocker is properly designed, and is on that same perpendicular plane, which is what my previous drawing shows. That "longer lever" offsets the effect of the valve side "longer lever", and the ratio remains the same.
There are always losses in an overhead valve valvetrain, but it isn't because the ratio changes on a roller rocker. Shoe type, yes. Roller, no.
The work we did on installing the stud mounted roller rockers on the small block Mopar Indy LAX heads all those many years ago, and paying $20/hr to use another person's mill, allowed me to understand what you were, and are, talking about Mike. Was thinking about that all day yesterday how the ratio changes on the shoe type and not on the roller. Tough to understand that on the roller rocker arm it is the roller center and not the roller contact point on the valve tip that is the rocker length on the valve side.
IQ,
You claim that the roller centre determines the rocker length on the valve side.
Well how do you explain this: using longer than optimum pushrods in most cases, if not all, increases valve lift.
What changes in the movement of the rocker arm such that more valve lift is obtained?
You claim that the roller centre determines the rocker length on the valve side.
Well how do you explain this: using longer than optimum pushrods in most cases, if not all, increases valve lift.
What changes in the movement of the rocker arm such that more valve lift is obtained?
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