I find the discussion irrelevant. I have a fair amount of experience with engines in the 900+ hp range that use store bought, box stock rocker arms. They hold lash, don't break, and run just fine for multiple seasons. So that covers about 99.5% of what anyone on this board is doing. There might be only one or two guys on this forum who run 1000+ hp stuff that require something special. Guys with 500, 600, or 700 hp engines don't need to move the shafts or machine the stands. All they need to do is buy a quality set of rocker arms and install them correctly.
Rocker arm recommendations?
- Thread starter dukeboy440
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I find the discussion irrelevant. I have a fair amount of experience with engines in the 900+ hp range that use store bought, box stock rocker arms. They hold lash, don't break, and run just fine for multiple seasons. So that covers about 99.5% of what anyone on this board is doing. There might be only one or two guys on this forum who run 1000+ hp stuff that require something special. Guys with 500, 600, or 700 hp engines don't need to move the shafts or machine the stands. All they need to do is buy a quality set of rocker arms and install them correctly.
Well, I'll admit what I know will fit on the head of a pin with a football field left over. But I have a question for you. I just had some major port work and 318 valves added to a slant six head. Those valves are "somewhere" on the order of .300" longer than the slant six valves. I wanted that for a multitude of reasons up to and including the larger valves and the longer stems for a better selection of some real HP valve springs. Are you saying I didn't need to relocate the rocker shaft? For a difference of .300"?
Just know I don't have a dog in this hunt, but you seem to be basically dismissing everything Mike does. Am I misconstruing that?
B3,
Somehow I don't think you are going to get it.....
Post 67, where you are fixated with [ wrongly, for the umpteenth time ]: 'The length remains the same'.
It is not what I have written that is utter & complete nonsense....
You talk about ratio changing because valve lift is lost. Yes, you got that right. Ratio change. Buuuuut that is not the only thing that happens with the rocker going from valve closed to valve open. Two other things happen concurrently:
- both the p'rod side & valve side travel through arcs. There is lost motion on both sides of the rocker due to the arc motions that are transferring a circular motion into a straight line [ prod & valve move essentially in a straight line ]. Depending on how the particular rocker is dimensioned will affect if & how much valve lift is lost.
- using a ball/ball prod as an example. The prod ball is a smaller radius than the rocker cup. How do we know? Because if the ball was bigger, it would not fit inside the cup, or would jam. The ball makes point contact inside the cup; the ratio on the prod side is that length from that point of contact to the fulcrum centre. And it changes as the rocker moves through it's cycle, changing the ratio on the prod side. And the position of the contact point in the arc also causes a change in rocker movement & therefore ratio.
The combination of the change in the arc plus the contact point of the prod & roller tip is what gives the overall ratio & it changes throughout the rocker travel.
This is how the Crane quick lift rocker works; the prod cup is lower. That actually looses some straight line motion [ prod ] because of being further down the arc; but counteracting this is the fact that the ball contact in the cup is closer to the fulcrum pivot. The ball contact position wins out & creates the early lift increase.
For those trying to understand the ratio change on the valve side. Imagine a shoe type rocker that is identical in shape to a roller tip rocker. Grind the shoe on the rocker to the same radius as the roller on the roller rocker. Now using the shoe rocker, the point of contact on the shoe changes during the rocker cycle. The ratio is the distance from the fulcrum centre to the shoe contact point it changes. Exactly the same thing happens with a roller rocker; it is as if at any time in the lift cycle, the roller is welded to the rocker arm & is as one.
Somehow I don't think you are going to get it.....
Post 67, where you are fixated with [ wrongly, for the umpteenth time ]: 'The length remains the same'.
It is not what I have written that is utter & complete nonsense....
You talk about ratio changing because valve lift is lost. Yes, you got that right. Ratio change. Buuuuut that is not the only thing that happens with the rocker going from valve closed to valve open. Two other things happen concurrently:
- both the p'rod side & valve side travel through arcs. There is lost motion on both sides of the rocker due to the arc motions that are transferring a circular motion into a straight line [ prod & valve move essentially in a straight line ]. Depending on how the particular rocker is dimensioned will affect if & how much valve lift is lost.
- using a ball/ball prod as an example. The prod ball is a smaller radius than the rocker cup. How do we know? Because if the ball was bigger, it would not fit inside the cup, or would jam. The ball makes point contact inside the cup; the ratio on the prod side is that length from that point of contact to the fulcrum centre. And it changes as the rocker moves through it's cycle, changing the ratio on the prod side. And the position of the contact point in the arc also causes a change in rocker movement & therefore ratio.
The combination of the change in the arc plus the contact point of the prod & roller tip is what gives the overall ratio & it changes throughout the rocker travel.
This is how the Crane quick lift rocker works; the prod cup is lower. That actually looses some straight line motion [ prod ] because of being further down the arc; but counteracting this is the fact that the ball contact in the cup is closer to the fulcrum pivot. The ball contact position wins out & creates the early lift increase.
For those trying to understand the ratio change on the valve side. Imagine a shoe type rocker that is identical in shape to a roller tip rocker. Grind the shoe on the rocker to the same radius as the roller on the roller rocker. Now using the shoe rocker, the point of contact on the shoe changes during the rocker cycle. The ratio is the distance from the fulcrum centre to the shoe contact point it changes. Exactly the same thing happens with a roller rocker; it is as if at any time in the lift cycle, the roller is welded to the rocker arm & is as one.
Bad assumptions lead to false conclusions. The bill was originally $30. It was reduced to $25 and $3 dollars were returned to the men in the room....$28. Each man had then paid $28/3 or $9.3333333. Not $9. 28+2=30. Edit...this is wrong.....as pointed out below in post #82..... 25 to the manager, 3 to the men and 2 to the employee = 30. Fire the employee and let the 3 men fight it out over the 5 bucks.
My only regret over the above is Bewy will conclude that because I was wrong about the money that I am also wrong about the rocker action.
This still correct.................
Ahh... but the roller is not welded.
To assume that the roller tip acts as if it was welded is wrong. The roller always transmits the force in a line parallel to the valve stem from the center of the roller.
I should add that this is assuming that whoever did the valve job got the tip perpendicular to the valve stem. Otherwise the force from the roller center will be applied perpendicular to the valve tip angle and generate side forces on the valve stem.
There will still be doubters and all things will still add up to $1 missing.
My only regret over the above is Bewy will conclude that because I was wrong about the money that I am also wrong about the rocker action.
This still correct.................
Ahh... but the roller is not welded.
To assume that the roller tip acts as if it was welded is wrong. The roller always transmits the force in a line parallel to the valve stem from the center of the roller.
I should add that this is assuming that whoever did the valve job got the tip perpendicular to the valve stem. Otherwise the force from the roller center will be applied perpendicular to the valve tip angle and generate side forces on the valve stem.
There will still be doubters and all things will still add up to $1 missing.
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I already had it. And, once I learned something different, and confirmed it with dyno testing, I dropped the old way like a bad habit. Not going back, either. If you did a bit more research, especially concerning mid lift geometry, you might come away with a different perspective. Only a refusal to learn/change will stop someone from understanding the concept.
Ummm, what?
Bewy, you are dillusional, I never said anything remotely close to that. Either that, or you don't really believe this stuff and just want to keep yanking my chain to get a response. Your credibility is taking a serious hit when you can't quote me accurately in the same thread. No wonder you got Smokey's quotes wrong too.
Where have I heard this before? Oh yeah, in my tech articles, as well as in this thread which is my previous quote. That is called sweep losses, and not ratio loss. Thanks for confirming my work.
And yet, there is a straight line through the pushrod and the center of the adjuster radius, no matter where the rocker is in it's arc motion. But we are not to believe that the center is the point of rotation. SMH.
If this was the case, it would be impossible for the rocker manufacturer to design a specific rocker ratio, so all those rockers advertised with a ratio is a lie.
The Crane rockers are a stud type rocker that has a lower pushrod seat, which, with a given pushrod length, will raise the fulcrum and increase rate of lift and velocity off the seat. I can do that with any rocker by raising the fulcrum point. The problem is, it does the exact same thing on the other side of the cam lobe, and closes the valve so fast it increases the probability of valve bounce and beats the seats out of the head. Just what everyone wants, right?
There you have it! Throw all those roller rockers in the trash. There is no benefit to them.
This has been tried before (unsuccessfully), but just for entertainments sake, you should try it again. After all, who needs those extra moving parts that could fail if they aren't really needed.
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Bravo, Jim! Unless you find the root of the discrepancy, it is possible to reach an incorrect conclusion. That math question baffles a lot of people, but you are a pretty smart cookie. Now, if Bewey could only answer the other question I asked.
My take on this is:
Each paid $9 (10 - 1 = 9) --> $27 total. Of the $27 paid, $25 went to the manager and $2 to the employee.
You have to subtract the $2 from the $27, not add it.
Yes, my solution of 9.33333 paid is incorrect. You have it simpler and more correct. $25 to the motel, $3 to the men and $2 to the employee equals $30. Much better.
I farted. Did that clear it all up?
I agree......
Innovation is dumb........
I'm just glad you didn't think so when you designed that timing cover that I like so much. As I think back though, the stock tin ones that I modified were working without any problems.
I guess your timing covers are superfluous for 99.5% of us? Yeah, probably.
However, I'll keep recommending them.
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Oh boy, where to start. First I will say that Jim (IQ52) is a much better diplomat than I am. Where Jim gently chides, I'm ready for a scorched earth approach. I had to wait all day to answer this post, because I was afraid I would say something I would later regret. But then, I realized that it's not so bad. I can just do a break down analysis of what Andy said.
By this non answer, I have given my answer. //Why would someone want to deflect from answering a yes or no question to which they know the answer? This is rhetorical, because I know the answer.
Look at me. I'm better than you because I've built 900+ horsepower engines. It's why only my opinion is important when someone asks about rocker arms. See post #69.
And, they give you time to admire the tail lights on that Chevy, because he paid attention to the details.
And those guys are special. They are the only ones who deserve to have it right.
Because you are what's irrelevant. Just buy what your told and bolt them on. After all, they're good enough for you peons.
I left this rather broad and unspecific, so run out and buy my book that will give you the additional information, and it may not be clear on "installed correctly". Oh, and it will introduce you to a bunch of products from my company also. Sorry, I don't have anything for relocating rocker shafts, so you'll just have to live with what you get.
/
/
/
I'm sure this isn't what you are consciously trying to say (I hope), but boy it sure does come across that way. I could have brought up a lot more, like "Why does Andy only comment on the big block forum? Doesn't he care about small block guys too"?, but I'm trying to be very reserved.
I was wondering, if I mow my 900 acre lawn with lawn shears, because I can, does that make a lawn mower irrelevant for someone who has a 400-800 acre lawn? Asking for a friend. Oh, and what's hyperbole?
By this non answer, I have given my answer. //Why would someone want to deflect from answering a yes or no question to which they know the answer? This is rhetorical, because I know the answer.
Look at me. I'm better than you because I've built 900+ horsepower engines. It's why only my opinion is important when someone asks about rocker arms. See post #69.
And, they give you time to admire the tail lights on that Chevy, because he paid attention to the details.
And those guys are special. They are the only ones who deserve to have it right.
Because you are what's irrelevant. Just buy what your told and bolt them on. After all, they're good enough for you peons.
I left this rather broad and unspecific, so run out and buy my book that will give you the additional information, and it may not be clear on "installed correctly". Oh, and it will introduce you to a bunch of products from my company also. Sorry, I don't have anything for relocating rocker shafts, so you'll just have to live with what you get.
/
/
/
I'm sure this isn't what you are consciously trying to say (I hope), but boy it sure does come across that way. I could have brought up a lot more, like "Why does Andy only comment on the big block forum? Doesn't he care about small block guys too"?, but I'm trying to be very reserved.
I was wondering, if I mow my 900 acre lawn with lawn shears, because I can, does that make a lawn mower irrelevant for someone who has a 400-800 acre lawn? Asking for a friend. Oh, and what's hyperbole?
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Oh Lort.
This almost made me snort my water up the wrong way. Best laugh of the day. Thanks.
B3,
I'm 'delusional'? Your quote in post 80 where you make this claim about what I supposedly said is ACTUALLY A QUOTE FROM YOUR POST IN POST 67, not mine.
Whose delusional.
Your post #80: 'There is a straight line through the pushrod & the centre of the adjuster radius'. Huh? How does a radius become a straight line?
Also in post #80: '....it would be impossible for the manufacturer to design a specific rocker ratio, so all those rockers advertised with a ratio is a lie'.
The ratio is a nominal ratio. The actual ratio can & does vary throughout the lift cycle. The Crane quick lifts are but one example. David Vizard's testing shows this in a number of ways. Not one of the 24 rockers tested produced the advertised ratio by using the formula of total valve divided by total lobe lift. He calls it the overall ratio ratio; another term would be the average ratio. Average because the ratio varies through the cycle; & somewhere in the cycle, dividing the valve lift by the amount of lobe lift gives the advertised ratio.
You do not seem to understand even the basics.
I'm 'delusional'? Your quote in post 80 where you make this claim about what I supposedly said is ACTUALLY A QUOTE FROM YOUR POST IN POST 67, not mine.
Whose delusional.
Your post #80: 'There is a straight line through the pushrod & the centre of the adjuster radius'. Huh? How does a radius become a straight line?
Also in post #80: '....it would be impossible for the manufacturer to design a specific rocker ratio, so all those rockers advertised with a ratio is a lie'.
The ratio is a nominal ratio. The actual ratio can & does vary throughout the lift cycle. The Crane quick lifts are but one example. David Vizard's testing shows this in a number of ways. Not one of the 24 rockers tested produced the advertised ratio by using the formula of total valve divided by total lobe lift. He calls it the overall ratio ratio; another term would be the average ratio. Average because the ratio varies through the cycle; & somewhere in the cycle, dividing the valve lift by the amount of lobe lift gives the advertised ratio.
You do not seem to understand even the basics.
IQ,
Your post 79: 'To assume that the roller tip acts if it was welded is wrong'.
So what would happen to the open & closing cycle IF the roller tip was welded??
Other than the roller skidding across the valve tip, the rocker action, rate of lift, motion etc would be exactly the same as if the roller tip was able to rotate.
My point was to demonstrate that throughout the rocker's cycle, the actual contact point of the roller [ on the valve tip ] changes. It is this point of contact of the roller to the fulcrum pivot [ this length ] that determines the valve side ratio. It changes & is NOT constant. It is triangle: [1] one side goes from the fulcrum pivot to the roller pivot [ & I presume this length is used to calculate the advertised ratio ]; another side [2] goes from the fulcrum pivot to the point of contact on the valve tip; the third side [3] goes from the roller pivot to the contact point on the valve tip.
[2] & [3] change throughout the cycle.
'The rocker always transmits the force in a line parallel to the valve stem from the center of the roller'. Yes, correct. But that is the FORCE. Not the ratio, see above.
Your post 79: 'To assume that the roller tip acts if it was welded is wrong'.
So what would happen to the open & closing cycle IF the roller tip was welded??
Other than the roller skidding across the valve tip, the rocker action, rate of lift, motion etc would be exactly the same as if the roller tip was able to rotate.
My point was to demonstrate that throughout the rocker's cycle, the actual contact point of the roller [ on the valve tip ] changes. It is this point of contact of the roller to the fulcrum pivot [ this length ] that determines the valve side ratio. It changes & is NOT constant. It is triangle: [1] one side goes from the fulcrum pivot to the roller pivot [ & I presume this length is used to calculate the advertised ratio ]; another side [2] goes from the fulcrum pivot to the point of contact on the valve tip; the third side [3] goes from the roller pivot to the contact point on the valve tip.
[2] & [3] change throughout the cycle.
'The rocker always transmits the force in a line parallel to the valve stem from the center of the roller'. Yes, correct. But that is the FORCE. Not the ratio, see above.
Because as the tip rolls the moment is transfer to the roller center. Thereby maintaining the pivot length of the rocker on the the intake side. Sorry I only graduated (barely) from high school. I have no degrees in anything so this is as clear as I can make it.
yellow rose
Overnight Sensation
Of course the ratio is nominal. If the rocker is made exactly at the nominal ratio it won’t be “nominal” under load. You are confusing two separate issues and you are wrong doing both.
IIRC the 1.6 “nominal” ratio rockers I run measured 1.66 or close to that with no load. With a load on them they are right at 1.6 like they should be.
My Norris W2 1.6 rockers measure damn near 1.7 on the intake and 1.65 or close to that on the exhaust. Under load they both measured 1.6 on the money.
You are way over your skis on this.
I fixed the one quote that I accidently forgot to put my name in. I figured you would know the difference. Wrong again, apparently. Btw, whose delusional? It's not my delusional. Maybe it's Jim's delusional, or Yellow Rose's delusional. I know! It's RRR's delusional. He's right proud of his delusional, too. Now, who's delusional? That would still be you.
Just like anything that rotates on the outer edge of a true radius, it revolves around the center and maintains a straight line with the axis. Melbourne and Brisbane and Perth and Sydney are all at different locations on the radius of the Earth, but (adjusting for topical elevation variations) they all are the same distance from the Earth's axis, and rotate around it. It doesn't matter whether it is daytime, or nighttime, it's still the same distance from the center. The pushrod centerline revolves around the center of the adjuster pivot axis, so even though it is at a different point on the radius, it is still directly in line with the axis or center. One only has to observe the pushrod in action to recognize this.
I know what a nominal ratio is. Remember, I do have my own design made by T&D. But, your idea of a nominal ratio is like taking the rocker designer outside, in the dark, blindfolded, spun in a circle until dizzy, handed a gun, and told to shoot a flea off a dog's nose in the next town over. You said "somewhere in the cycle", like ratio-ing rockers is akin to a Chinese auction. Buy them, and then find out what you got.
The setup has a lot to do with the losses of valve lift. Rocker geometry will play a huge role in how much wasted motion is in the system. I know an engine builder who puts a ridiculously short pushrod in his lift rule engines to pass tech, and then swaps them to longer pushrods for the race. He reduced the lift by inducing way more wasted motion into the system. Does that mean the rocker changed it's length, or ratio. No, the rocker was already designed and manufactured. It didn't experience some magic or miracle. It experienced a user manipulating it's function. The roller position didn't get any further from the fulcrum centerline, and neither did the adjuster. I already see you disagreeing, so tell me. If you rotate that rocker until the roller is directly below the fulcrum centerline, what is the ratio, and did the valve side lever completely disappear since it now has zero length, according to your logic?
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B3,
It is a pity you cannot mount an argument without resorting to insults & name calling. Includes your cheer squad [ not IQ52 ].
I am not sure what you mean by your last sentence in the above post. If you mean the rocker is pretty much vertical [ prod side up in the air ] when it is normally ~ horizontal, then yes valve side has zero length.
And you are still not getting it....
The engine builder you describe 'bending' the rules did indeed change the overall ratio. Which anybody with any common sense can see because the lobe lift remined the same, but valve lift changed with different length prods. Example, 1.5 ratio with short pushrods, 1.57 with long prods. How the change occurred, wasted motion you claim & I agree with that, is besides the point. The fact is that ratio change occurred.
And yes, you are right, the roller & the adjuster didn't get any further from the fulcrum centre. But what you keep failing to understand is the contact points DID change. And these contact points changed in your short/long prod example, which changed the valve lift, & the overall ratio.
If your theory was correct, a rocker arm's ratio at any given increment of lobe lift will always be the same. It is not & this is known from measurements taken.
It is a pity you cannot mount an argument without resorting to insults & name calling. Includes your cheer squad [ not IQ52 ].
I am not sure what you mean by your last sentence in the above post. If you mean the rocker is pretty much vertical [ prod side up in the air ] when it is normally ~ horizontal, then yes valve side has zero length.
And you are still not getting it....
The engine builder you describe 'bending' the rules did indeed change the overall ratio. Which anybody with any common sense can see because the lobe lift remined the same, but valve lift changed with different length prods. Example, 1.5 ratio with short pushrods, 1.57 with long prods. How the change occurred, wasted motion you claim & I agree with that, is besides the point. The fact is that ratio change occurred.
And yes, you are right, the roller & the adjuster didn't get any further from the fulcrum centre. But what you keep failing to understand is the contact points DID change. And these contact points changed in your short/long prod example, which changed the valve lift, & the overall ratio.
If your theory was correct, a rocker arm's ratio at any given increment of lobe lift will always be the same. It is not & this is known from measurements taken.
yellow rose
Overnight Sensation
The funny this is I pointed this out LONG a ago in this thread. That’s why the manufacturer gives you a protrusion length for the adjuster. For the correct ratio and oiling.
You can manipulate the ratio by changing the adjuster position, but that doesn’t make it the right thing to do. Which by the way is the exact example Mike just gave you.
I hope that wasn’t to insulting to you, but redundancy makes me irritable.
Insults and name calling? Let's take a walk back in time to post #8 where you insulted my knowledge and value by encouraging people, in a public open forum, to not give credence to ANY advice I might give. If not for that unprovoked insult, you likely wouldn't have heard a peep out of me on this thread. I've given you ample opportunity to backtrack enough to still disagree with my tech article, but concede that I am a thinker and might actually have valuable input. I was very nice and professional with my initial responses, but it is clear you have no shame for your insults, so you have escalated the tension in this discussion. When you make such attacks, it isn't just against me, but the livelihood of my family as well.
For what it's worth, I am not name calling. I have called a spade a spade. You started off with the insult, then when confronted with the misrepresentations of Smokey's quotes, you pivoted the argument elsewhere. You used Smokey as a reference, and when shown that wasn't what he said, you continue to make the same arguments, just without referencing Smokey. Then, you started quoting me as saying things that I didn't say, and when called on it, you tried to make it appear that I was the one to blame. You dragged other people into the argument trying to make a case that was shown repeatedly to be flawed with CAD drawings, debate, explanations, and referral to other references that also make the case in point, ie, the Reid Rockers video link, mid lift geometry info, etc. (Did you actually follow up on these?). That qualifies as a psychological condition called delusion. That's simply a recognition of behavior, and not just attaching a name to be spiteful. Maybe you're not delusional, but you're missing out on a great acting career.
As stated previously, I have already seen, analyzed, and discounted with mathematical and practical application, everything you have been saying or referring to. You don't seem to have taken the time to digest the alternative view, whether it be from me, someone else on this thread, or the thousands of other professionals around the world who have the same views, if you only looked for them. After all, you like the strength in numbers approach.
That's a bold statement, because I can hold one in my hand at that angle and clearly see the valve side lever. It didn't disappear at all. It's still the same length as it was before. You seem to be saying that a rocker requires a relationship to a static linear object to have a ratio, in this case the valve stem. Again, that would be incorrect and make it impossible to ratio a rocker at manufacture.
He didn't change the ratio, he changed the lift. He increased the inefficency of the set up, It didn't morph the rocker into something different. And, how do you know the lobe lift remained the same? The pushrod sweeps too, so did you measure the rocker input to see if it stayed the same? You are in way over your head.
Assigning dimension to one part by measuring a different part is misguided. If you actually measured the input at the rocker vs. the output at the rocker (not the valve), you would find the ratio is exactly the same, which is shown in my CAD drawing. To see the real results of ratio, the measurements have to be taken through the same arc as the input and output arcs, not in the straight line of the valve stem. The straight lines simply show the inefficiencies of converting arc motion to linear motion, and those inefficiencies can be manipulated to a great degree, hence the engine builder reference. This, by the way, is also addressed in my tech articles, but you must have missed that part.
The contact points changed, but the arc remained the same. Exactly as I showed in my Earth example. If the arc is the same, the ratio is the same. A shoe type rocker increases the arc, a roller does not.
No, rocker input, not lobe lift. Have you verified input? See above. Linear to arc, arc to linear. The inefficiencies are on both sides, but, and you knew I was going to say this, the ratio stayed the same.
The longer this goes on, I believe, the more credibility I gain. Thank you for that. Unfortunately, I'm thinking the more you lose, also.
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B3 [ Mike].
Wow! Don't let the facts get in the way of a good story!
Misrepresenting Smokey? Really? A figment of your imagination. I got involved in this post because of your claim that rocker ratio remains constant on the valve side. It does NOT & have said so ever since; & neither does the prod side remain constant.
In post 36, I quoted SY. In my Smokey book the quote is on page 88. I did not not misquote him, it is exactly what he said word for word, & it relates to ratio change, the subject at hand. I find it insulting that you claim I misrepresented a famous icon. So now maybe we are even....
0000s agree with your theory. Yeah well.....
0000s of professionals, at one time, also agreed that the earth was flat....
So the fella that changed from short to long prods, changed the lift, but not the ratio? You say. The effective or working ratio must have changed to change the lift. And how could the lobe lift change [ which you are suggesting ] if all he changed was pushrods?? Common sense, please. The quoted/advertised ratio might only occur at one point in the lift cycle.
I dragged other people into this thread? No, they dragged themselves into it.
And now you are a psychologist as well!!
'If the arc is the same, the ratio is the same'. That is wrong & really surprised you say it. The arc on a roller rocker is the arc described by the movement of the roller centre. That arc is the arc of a circle whose radius is from the fulcrum centre to the roller centre. Say as an example the radius is 1.5". The point of contact of the roller on the valve tip may at one point in the cycle equal the 1.5" radius, but at other points it can & will be more or less than 1.5". This varying distance is what gives you the ratio on the valve side & is NOT constant.
A shoe rocker that has the shoe ground to the same circumference as the roller on a roller rocker, & is identical in other aspects, will behave identically as the roller rocker.
There is no better example of ratio change than to look at high mileage factory rockers, where usage has left a mark on the shoe. It is never a thin line, it is a thick section typically 1/8" wide or wider. That shows the differing contact point during the rocker cycle....& changing ratio.
Mike, I have a suggestion. I see you have an email address. How about I email you some drawings about what I am saying.
Wow! Don't let the facts get in the way of a good story!
Misrepresenting Smokey? Really? A figment of your imagination. I got involved in this post because of your claim that rocker ratio remains constant on the valve side. It does NOT & have said so ever since; & neither does the prod side remain constant.
In post 36, I quoted SY. In my Smokey book the quote is on page 88. I did not not misquote him, it is exactly what he said word for word, & it relates to ratio change, the subject at hand. I find it insulting that you claim I misrepresented a famous icon. So now maybe we are even....
0000s agree with your theory. Yeah well.....
0000s of professionals, at one time, also agreed that the earth was flat....
So the fella that changed from short to long prods, changed the lift, but not the ratio? You say. The effective or working ratio must have changed to change the lift. And how could the lobe lift change [ which you are suggesting ] if all he changed was pushrods?? Common sense, please. The quoted/advertised ratio might only occur at one point in the lift cycle.
I dragged other people into this thread? No, they dragged themselves into it.
And now you are a psychologist as well!!
'If the arc is the same, the ratio is the same'. That is wrong & really surprised you say it. The arc on a roller rocker is the arc described by the movement of the roller centre. That arc is the arc of a circle whose radius is from the fulcrum centre to the roller centre. Say as an example the radius is 1.5". The point of contact of the roller on the valve tip may at one point in the cycle equal the 1.5" radius, but at other points it can & will be more or less than 1.5". This varying distance is what gives you the ratio on the valve side & is NOT constant.
A shoe rocker that has the shoe ground to the same circumference as the roller on a roller rocker, & is identical in other aspects, will behave identically as the roller rocker.
There is no better example of ratio change than to look at high mileage factory rockers, where usage has left a mark on the shoe. It is never a thin line, it is a thick section typically 1/8" wide or wider. That shows the differing contact point during the rocker cycle....& changing ratio.
Mike, I have a suggestion. I see you have an email address. How about I email you some drawings about what I am saying.
famous bob
mopar misfit
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^this .
yellow rose
Overnight Sensation
Did you watch the webinar I posted in the Race Forum? Darrell Reid gives an explanation of this. If you don’t know who he is, you may want to see what he builds.
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