Pushrod to Roller Rocker geometry?

[Pops1967GTX]

 

[BSB67]

To the OP - There is some good and accurate info in this thread, and there is some info that is totally incorrect. You'll need to sort through it if you are compelled to "fix" something.

Here are other thoughs for you to consider:
If you change nothing from what you posted initially, your motor and valvetrain will live a long and happy life. The HS are very good and buying a different roller rocker would not change in any meaningful way the valve side rocker geometery. The valve side geometery would get better if you went with a non-roller tip rocker.

Some of the posts that speak to the lack of perfection and associated fix to valve side roller rocker geometery are correct. You'll just need to decide the relative importance of this lack of perfection, and whether you want to chase after it or not.

You or someone were correct in thinking that the pushrod length changes geometery. However, it only changes the geometery on the pushrod side of the rocker, not the valve side. Apparently, only the valve side geometery is of importance or discussed.

 

[Steve009]

Check your sweep pattern first on the valve stem, if this is too wide or too far off to the side you will require to relocate the rocker shaft. (most of the time with roller rockers you need to raise and move away from the valves)
I used the B3 kit to set mine to center and minimal sweep, see pictures.

By doing so you alter the length of the push rod.
Pushrod length does not change any geometry, the length is determined after the geometry is set.
Go for an as long as possible push rod, depending on the way of oiling (through lifter or from rocker arm) you will need to ensure the oiling hole in the rocker arm can reach the cup, if the cup sits too high it might not get oil from the oiling hole. But in that case it would be a design flaw of the rocker arm as it will force you to have multiple adjuster threads below the rocker arm.

If your push rod would be "short" you need to increase the length of the adjuster below the rocker arm, by doing so you will increase the "side way" motion of the push rod which will make you loose valve lift and puts a bigger angle between the adjuster and push rod which increases the side load on the ball/cup.

View attachment 1198745 View attachment 1198746

by sweep pattern are you referring to the contact line on the valve tip that the roller makes (cover in marker and run through a few cycles)? If so, mine seems to be dead on without any shims.

 

[Steve009]

To the OP - There is some good and accurate info in this thread, and there is some info that is totally incorrect. You'll need to sort through it if you are compelled to "fix" something.

Here are other thoughs for you to consider:
If you change nothing from what you posted initially, your motor and valvetrain will live a long and happy life. The HS are very good and buying a different roller rocker would not change in any meaningful way the valve side rocker geometery. The valve side geometery would get better if you went with a non-roller tip rocker.

Some of the posts that speak to the lack of perfection and associated fix to valve side roller rocker geometery are correct. You'll just need to decide the relative importance of this lack of perfection, and whether you want to chase after it or not.

You or someone was correct in thinking that the pushrod length changes geometery. However, it only changes the geometery on the pushrod side of the rocker, not the valve side. Apparently, only the valve side geometery is of importance or discussed.

thanks for this explanation. Filtering through the correct and incorrect statements would be impossible for me saying since I’m just learning all of this for the first time. Happy to hear if left it as is I’ll most likely be ok. I do appreciate learning about the finer details as well though.

 

[dvw]

People way to much about geometry on mild cams. Theyve been running stick shaft locations for 60 years+. Make sure the adjuster isn't out to far. Make sure the pushrod and cup diameter are the same. Send it. Plenty more important items to worry about. He'll I've run close to .700" with the stock pivot location. Which is where the change needs to be made with a given rocker arm, lift, and stem height. You don't gain much dialing it in dead nuts under .600" unless the components you chose are really poor.
Doug

 

[Steve009]

People way to much about geometry on mild cams. Theyve been running stick shaft locations for 60 years+. Make sure the adjuster isn't out to far. Make sure the pushrod and cup diameter are the same. Send it. Plenty more important items to worry about. He'll I've run close to .700" with the stock pivot location. Which is where the change needs to be made with a given rocker arm, lift, and stem height. You don't gain much dialing it in dead nuts under .600" unless the components you chose are really poor.
Doug

I’m at .600” almost dead on. Fairly aggressive cam but certainly not full blown drag car kind of stuff. I see what you mean. If it was a drag car then go crazy but for high performance street it’s less important.

 

[Wietse]

by sweep pattern are you referring to the contact line on the valve tip that the roller makes (cover in marker and run through a few cycles)? If so, mine seems to be dead on without any shims.

Indeed, the contact pattern should be narrow and near the center area of the valve stem.
Depending on the brand/model rocker arms some might be close, some might be way out.
Mine were not so ideal so i used the B3 kit and reduced the sweep pattern by more than half i believe.
Some might disagree on getting this set up as correct as possible, though while you are at it why not make it as best as you can?
Going to roller rockers moves the pivot point of the arm up by .125" (with .250" diameter roller) from the base position which is ideal for a standard stamped rocker arm but can change things quite a lot for a roller type.
I did not see you mentioned how wide and where your sweep pattern is but depending on that i would decide how to proceed.

 

[IQ52]

Is it wise to reference a video that uses a stud mounted rocker arm system when the OP is using shaft mounted rocker arm system?

 

[BSB67]

I’m at .600” almost dead on. Fairly aggressive cam but certainly not full blown drag car kind of stuff. I see what you mean. If it was a drag car then go crazy but for high performance street it’s less important.

If it is a flat tappet cam with spring pressures 150 at the seat, 370 open, and net lift is 0.570", that would not be considered "agressive". It might be fairly large, but not aggressive.

You'll be fine.

 

[Steve009]

Indeed, the contact pattern should be narrow and near the center area of the valve stem.
Depending on the brand/model rocker arms some might be close, some might be way out.
Mine were not so ideal so i used the B3 kit and reduced the sweep pattern by more than half i believe.
Some might disagree on getting this set up as correct as possible, though while you are at it why not make it as best as you can?
Going to roller rockers moves the pivot point of the arm up by .125" (with .250" diameter roller) from the base position which is ideal for a standard stamped rocker arm but can change things quite a lot for a roller type.
I did not see you mentioned how wide and where your sweep pattern is but depending on that i would decide how to proceed.

I’m going to test the sweep pattern again and take pictures to share

 

[B3RE]

Here are other thoughs for you to consider:
If you change nothing from what you posted initially, your motor and valvetrain will live a long and happy life.

You can't possibly know this. Even motors on the verge of absolute perfection can fail.

The HS are very good

From an engineering perspective, meh, not so much.

and buying a different roller rocker would not change in any meaningful way the valve side rocker geometery.

Actually, it can be quite substantial between brands.

Apparently, only the valve side geometery is of importance or discussed.

Both sides are important, but the pushrod side is less important, and designed into the rocker and that limits what you can do to make it better, unless you buy a custom rocker.

People way to much about geometry on mild cams. Theyve been running stick shaft locations for 60 years+.

The old adage of "it's hard to teach an old dog new tricks" is very relevant.

He'll I've run close to .700" with the stock pivot location. Which is where the change needs to be made with a given rocker arm, lift, and stem height.

This makes it sound like the higher the lift, the worse the geometry, when the opposite is actually true with a roller rocker. When I see these claims, I know someone doesn't fully grasp what true rocker geometry really is.

You don't gain much dialing it in dead nuts under .600" unless the components you chose are really poor.
Doug

Do you mean like the design of most every Mopar roller rocker design, including HS, or the incorrect stand location in most every head for those rockers?

I'm not trying to cause a fight, but I don't like seeing misinformation that has been responsible for a lot of damage over the years. I used to get away with some pretty sketchy stuff in my younger years, but I also busted a lot of stuff unnecessarily as well. I'm glad I changed with the technology and knowledge available, and I don't take those risks anymore.

To the OP, read the tech articles (multiple times if necessary), and see if they make sense. I will guarantee it is more logical than the other Mopar valvetrain info that has been around for the past fifty years.

 

[B3RE]

Mike at B3 Racing. He just joined our site a couple of months ago. He is a very knowledgable and helpful guy. Some very good reading in his tech tab on his website.
http://www.b3racingengines.com/

Actually, I joined back in 2013. I've just been an observer until recently. Thanks for the kind words.

 

[dvw]

Not that geometry doesn't matter. But this stuff has been around a long time working ok. Now let's have some real world numbers of performance gains and failures from less than optimal geometry?
Doug

 

[RemCharger]

These are trickflow 240s with the trickflow "recommended part #" rockers?

i did not know this. I always thought pushrod length is what changed the contact patch on the valve tip. As for the angle of the pushrod to the ball tip on the adjustment screw, is there anyway to know if the angle I have is ok?

 

[B3RE]

Not that geometry doesn't matter. But this stuff has been around a long time working ok. Now let's have some real world numbers of performance gains and failures from less than optimal geometry?
Doug

I get it. Muzzle loaded rifles also have been around for a long time, and they work ok. But, if I had to go into battle, I'd be carrying a M16 or something similar.

Let's see some real world performance results of running a full groove main bearing vs a half groove. They are recommended often, but I see no performance increase from them. I suppose one would make the argument that they help the rod bearings live, and that is true in some cases, but geometry is essentially the same thing by giving an increase in durability through valvetrain stability. I don't claim a performance advantage, although there usually is one, but I'm more interested in it being right.

I have done back to back dyno testing and saw an extra 600 rpm, and 46 hp from correcting the geometry on a small block. And, it was on one of those low (.530") lift applications that don't gain much from making it "dead nuts". I would have to ask what the definition of "dead nuts" is, which someone would have to know in order to get there, and a centered pattern isn't it.

If anyone sits down and thinks about what the job of the rocker arm is, they will see how an efficient, properly set up rocker system will transmit the cam info to the valve the way the lobe was designed to do. The cam gives the orders, and the rocker arm is the messenger that delivers that info to the valve. If the rocker does not transmit that info in the most direct manner possible, then lobe information is lost in wasted motion. The stability is also part of the lobe design, and improper transmission of that lobe results in valvetrain instability due to acceleration and deceleration occurring at the wrong time.

 

[steve340]

A while ago I did the final assembly of a limited saloon engine - a 350 Chev. This class must use the stock style stamped steel rockers mounted on studs. At trial assembly the final valve lift with lash measured at the valve tip was 0.525 thou. This had been a running engine prepared by someone else so I set it up with the supplied pushrods that had been running in the motor. I tried my adjustable pushrod and by shortening the pushrod and adjusting the geometry of the rockers I ended up with 0.536 thou.
This was what the cam card said the lift would be and I was setting the cold lash at 0.015 thou.
Given - the rockers are probably over ratio than their advertised ratio - so that explains the final lift figure being up slightly. I shortened the pushrods 0.100 thou and picked up an extra 11 thou valve lift. Also the rockers at full lift were in a better place on the rubbing pad.
I don't know what that extra lift would come out as a HP/TQ figure wise on a dyno but I think you would notice an increase in all areas - low down torque and high rpm horsepower.
The little things all added up can make quite a difference - the difference between a sweet motor and an OK one.
On a shopping cart - yes sir don't get too carried away. But on a performance motor to say it makes no never mind is wrong IMO.

 

[Steve009]

These are trickflow 240s with the trickflow "recommended part #" rockers?

yes that’s correct

 

[BSB67]

You can't possibly know this. Even motors on the verge of absolute perfection can fail.

No more than you can can claim that it won't live a long and happy life. There are always extremes and exceptions Mike, but in the context of this discussion and application, I stand by my words. Experience does matter. I'm willing to wager that it will live a long and happy life. Are you willing to wager it won't?

From an engineering perspective, meh, not so much.

Engineering is not the only measure of a product.

Actually, it can be quite substantial between brands.

Because the of the factual nature of the differences between brands, we would likely agree on the differences. We probably would not agree on the significance of the "substantial" differences.

I understand the geometry. I'm not selling anything. I'm giving my open and honest opinion on a subject that I have experiance, and sharing it with those choosing to listen. They can make their own decision.

 

[Wietse]

The thing is that when Chrysler designed the engine they did their homework to make the geometry good and reliable.
When owners changed over to roller rockers etc. things change in dimensions and things don't run like it should.
It is up to the user to correct that to make it work "as designed", getting away with it for so many builds over the years does not mean it is good to do so.
By ignoring it you allow it to make bigger angles and increasing the side load, valves slamming shut or flying over the cam lobe because the velocity is not where it should be and parts moving too fast at either end of the valve stroke.
Those are facts that may occur, the severity is questionable and could be minimal depending on what parts/brands are used.
People spend 5-10K for an engine build and then take the risk of valve train issues, if something happens people wonder why, or this/that part is poor quality...anything to blame exept their own ignorance.
What time/money does it cost you to make it as it should over a complete engine build? Not much.

 

[B3RE]

No more than you can can claim that it won't live a long and happy life. There are always extremes and exceptions Mike, but in the context of this discussion and application, I stand by my words. Experience does matter. I'm willing to wager that it will live a long and happy life. Are you willing to wager it won't?



Engineering is not the only measure of a product.



Because the of the factual nature of the differences between brands, we would likely agree on the differences. We probably would not agree on the significance of the "substantial" differences.

I understand the geometry. I'm not selling anything. I'm giving my open and honest opinion on a subject that I have experiance, and sharing it with those choosing to listen. They can make their own decision.

I never made a claim that it wouldn't live a long and happy life. I just said it is wrong. It sounds like you are so confident the OP won't have a problem that you will pay for the repairs if he does. After all, you have no money invested in his build, yet you make a claim that you can't possibly know to be true. I didn't claim he would have a failure, only that the RISK of failure increases dramatically. If the geometry is correct, that is one more failure risk being removed from the equation.

We all have our experiences, and I've seen enough damage to know that it doesn't make sense to not make it right. The difference is, I see the experiences of hundreds of people who call AFTER something failed, and it's usually a painful (expensive) experience. The OP can make his own decision, and I only want it to be an informed one. I left plenty of time on this thread for someone to explain proper geometry, which you say you understand, and yet there was nothing substantial said. I don't have the time to lurk on every forum just waiting for someone to have a geometry question so I can sell them something. I have plenty of work to keep me busy. But, if I see where I can reduce the risk of failure, I speak up. I don't have to sell something. Jim (IQ52) could make something, if he can be talked into it. He knows what's up, and I wouldn't care if he did make it. But, if Jim won't do it, who else will? Oh, I forgot. It doesn't need it to be right.

As far the engineering not being the only measure of a product, what is it then? A shiny finish? So heavy it belongs on earth moving trucks? If it's designed (engineered) wrong, it is poor quality no matter what else you do to it. The brand makes no difference.

On the differences between rockers, do you suppose changing the pushrod length between brands by .100", all else being equal, is substantial? That is roughly the difference from the rocker design extremes, as well as about .120" valve lift difference when calculating the correct stand height. Sounds pretty substantial to me. But, you understand the geometry, so you already knew that.

Everyone has the right to voice their own experiences and opinions. I encourage that. But, if I sell a part and it CAUSES a failure, that's a liability on me. If someone else discourages a part and it results in failure, who carries the liability then? At that point, "I never had a problem" is of no consolation to the guy with the failure.

The fact that the OP has Trick Flow heads is a benefit because they raised the stands over where the factory and other aftermarket manufacturers are located. It will need much less correction. Now, if that position was not important, why would they bother? Just copy what everyone else did and go along with the crowd.