Roller tip rocker adjustment?

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19blockhead72

19blockhead72

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So I have always run stock rockers but decided for my current build I wanted something a little more sturdy so I picked up this set from a member. I put one on the shaft just to see how everything looked. This is how they set on the valve tip. Not really liking it too much, could this be a problem? It's a 408 with j heads and a 480ish lift cam. The rockers are stamped mopar performance. What do you think?
 
Yeah I see no pic.

But I assume the geometry is off. It's SUPER rare for roller rockers to just "line up". You can use a B3 geometry correction kit. Which is what YR would probably recommend.

Mark the top of the valves. Roll the engine over one full revolution. Look at your valves. If they look like this:

167691d1227760961-valve-tip-wear-pattern-valve.jpg


Not lined up. Big problems at top end.

If they look like this:

valvetip.jpg


Nice. Centered. No crazy movements. The contact area isn't crazy wide. Then your geometry should be good.

Here's a hot rod article that gets into it a little more.

Rocker Arm & Valve Train Geometry - Circle Track Magazine
 
19blockhead72 said:
It's way off, it's so disheartening but if it can be corrected at least I didn't throw my money away.

View attachment 1715040309
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Why's it disheartening? It's MUCH more rare NOT to have to correct the geometry then it is to correct it. I'd say a solid 7-8 engines need geometry corrected. So you're in the majority. So nothing to worry about. Very common.
 
Being off center is NOT important as long as it is not too far off. The force vector goes straight down into the valve's stem on a roller rocker; parallel to the center axis of the valve, and stays pointed straight down as the tip moves; that is the whole point of the roller tip design.

The 1st pix that Lustle shows is not going to be an issue at top end because the contact is off-center; it is going to be an issue due to the WIDTH of the patch. The width of the contact patch IS important as a narrow patch shows that the lost motion has been minimized as well as variations in tip velocity that go with a wide sideways motion.

The OP's patch width is hard to see. The off-center factor is more than I would like but I would also be looking hard at the pushrod side too, and where the pushrods ride in the pushrod holes. It may be that the overall rocker length is too long, and the pushrods are also being pushed too far inward towards the intake. Any attempt the move the whole rocker shaft inward to get the rollers more centered on the valve tips would make the pushrod side even worse.

OP, are these supposed to 1.5 or 1.6 ratio rockers?
 
I know it can be corrected, just spent a butt load of money
nm9stheham said:
Being off center is NOT important as long as it is not too far off. The force vector goes straight down into the valve's stem on a roller rocker; parallel to the center axis of the valve, and stays pointed straight down as the tip moves; that is the whole point of the roller tip design.

The 1st pix that Lustle shows is not going to be an issue at top end because the contact is off-center; it is going to be an issue due to the WIDTH of the patch. The width of the contact patch IS important as a narrow patch shows that the lost motion has been minimized as well as variations in tip velocity that go with a wide sideways motion.

The OP's patch width is hard to see. The off-center factor is more than I would like but I would also be looking hard at the pushrod side too, and where the pushrods ride in the pushrod holes. It may be that the overall rocker length is too long, and the pushrods are also being pushed too far inward towards the intake. Any attempt the move the whole rocker shaft inward to get the rollers more centered on the valve tips would make the pushrod side even worse.

OP, are these supposed to 1.5 or 1.6 ratio rockers?
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The rockers 1.5. I'll check to see how the pushrods look.
 
19blockhead72 said:
I know it can be corrected, just spent a butt load of money

The rockers 1.5. I'll check to see how the pushrods look.
Click to expand...


That's what Lustle was telling you. There is no such thing as correct geometry with any rocker right out of the box. There are many things that affect geometry, so no matter who tells you they bolted their stuff on, no matter how much the rockers cost, they probably needed to be corrected. You are the norm, not the oddball.


The fact that you are actually going to correct it is even better. Most guys just bolt them on and go and then wonder why their stuff doesn't run.
 
19blockhead72 said:
J head with a 480 lift.
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Who did the heads and where is the stem height set at? Around 1.917-37 off the top of my head is where it should be, taller the worse off when stuck with as cast stands...
Basically the taller the valve gets and or rocker shaft gets...the closer the two are to eachother. You can A. Cut the stem height down, B. Lower the rocker shaft by means of machining the stands about .080...Or C. Buy different rockers because sometimes they put the ratio on the wrong side of good and it hangs off the valve....Or D. Spend another butt load on B3 rocker shaft kit.
I call this skinning of the cat, meow now...
 
yellow rose said:
That's what Lustle was telling you. There is no such thing as correct geometry with any rocker right out of the box. There are many things that affect geometry, so no matter who tells you they bolted their stuff on, no matter how much the rockers cost, they probably needed to be corrected. You are the norm, not the oddball.


The fact that you are actually going to correct it is even better. Most guys just bolt them on and go and then wonder why their stuff doesn't run.
Click to expand...

Or they wonder HOW THE HECK did their valve train come apart when they are running 7K+ RPM with uncorrected geometry.

I have to disagree with nm9 about the off center shown in my first pic. Being that far off center is definitely going to be a problem. And the width of the patch, is part of it being off center. Properly centered the width of the contact patch would decrease. Here's a lunati page about it:

How to Verify Valvetrain Geometry - Lunati Power

Notice the off center patches are wider? But the center patch is smaller? Even though it's the same arms, just corrected geometry. That's because when it is off center, there is extra "scrubbing" of a sort. The rocker arm moves further along the valve stem than it should. Centering of the rocker tip to the valve THROUGHOUT the motion is the most important part.

You would be AMAZED how much a valve actually moves under the rocker arm. Especially at high RPM. The smallest amount of deflection in the valve train combined with the valve stem itself moving. Would cause failure in that setup. Here's an example of how much the valve moves. Warning, this video is filmed with a sort of "timing" light, so that you can still see the rocker/valve moving at high RPM. This does cause some pretty severe flashing at some points of the video.



It's also not valve float. There is valve bounce. I didn't make it entirely through the video. But I never saw valve float. Watch the tip of the valve stem. And it's contact with the rocker arm. That tip is MOVING. A small movement like that, with an off center contact patch like the first pic I posted. It's a recipe for disaster.
 
19blockhead72 said:
It's way off, it's so disheartening but if it can be corrected at least I didn't throw my money away.

View attachment 1715040309
Click to expand...
Just got a look at the pic. Something is drastically wrong here. I have never seen a MP rocker that long over the valve, especially on a small block. Are you sure they aren't big block rockers?
 
B3RE said:
Just got a look at the pic. Something is drastically wrong here. I have never seen a MP rocker that long over the valve, especially on a small block. Are you sure they aren't big block rockers?
Click to expand...
I was wondering that myself but don't have any idea how to tell.
 
Lustle said:
Or they wonder HOW THE HECK did their valve train come apart when they are running 7K+ RPM with uncorrected geometry.

I have to disagree with nm9 about the off center shown in my first pic. Being that far off center is definitely going to be a problem. And the width of the patch, is part of it being off center. Properly centered the width of the contact patch would decrease. Here's a lunati page about it:

How to Verify Valvetrain Geometry - Lunati Power

Notice the off center patches are wider? But the center patch is smaller? Even though it's the same arms, just corrected geometry. That's because when it is off center, there is extra "scrubbing" of a sort. The rocker arm moves further along the valve stem than it should. Centering of the rocker tip to the valve THROUGHOUT the motion is the most important part.
Click to expand...
Properly centered with the minimum sweep will only happen if the fulcrum length of the rocker is correct for the shaft location, so no, centered is not the most important. You are applying a stud type design, with the correct fulcrum length and that is adjusted by varying the pushrod length, to a shaft system that is not, and rarely if ever has the correct fulcrum length.

You are correct though, that the contact us way to far from center for reliable operation.
 
Is it possible that pushrods that are to small would do the same thing??

Jake
 
19blockhead72 said:
I was wondering that myself but don't have any idea how to tell.
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The small block will usually have the adjusters centered in the rocker body, and the big blocks will have a little over 1/8" offset.
 
MOPAROFFICIAL said:
Basically the taller the valve gets and or rocker shaft gets...the closer the two are to eachother.
Click to expand...
And here is where this post went off the rails. Everything after this is wrong when using a roller rocker.
 
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