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So you got that much movement with .040"?

I'd go another .015" and you should be centered up or close on the sweep... just gauging percent change with the .040"

...or are you done on that bit of adjusting?
 

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Discussion Starter · #82 ·
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Here is the geometry at midlift. It's a pain in the butt to try and get pictures. It DOES roll to the outside, then come back as it should. I dropped the 2nd pedestal off to get .042 taken off IT, then check 1,3,5 & 7. I asked the guy doing the machining if he had a way to mount them up to slot the pedestal mounting holes, and he said maybe, but he would just run them as they were and didn't think the pattern was too bad. He said he likes it kn the exhaust side, rather than the INTAKE side because he said it would be worse on the guides if it was pushing from the intake side.

I'll run back in to town when he calls me, and see what the driver side set looks like all bolted up, and then see if I need to pursue slotting the holes.

The wear pattern starts EXACTLY in the center of the valve stem. I guess I'd have to measure the wear marks widths and average them, and then slot the holes that much? I haven't really sat and looked to figure that out. It DOES seem like my thought a few weeks ago, that if I would have slotted the holes to mount the pedestals as they plopped in the head, INSTEAD of milling out clearance for the valve cover mounting, it would almost be perfect on the valve stem. 🙄
 

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But I do believe the correct geometry will deliver a sweep
that begins in the middle of the valve stem, and then returns
to the middle of the valve stem. . .Again, just my opinion.
Just thinking from the point of view of minimizing angular forces on the valve stem. Why is it important to have the rocker perpendicular to the valve stem at the beginning and the end of the movement? I would think that it would be best for the rocker tip to be at the center of the valve stem when the forces are the greatest. Which at first I thought would be at max lift when the spring pressures are the greatest. However, the more I think about it, the inertial forces are probably the highest when the cam lobe is at it's steepest angle and the valvetrain is accelerating at the highest rate (which may likely occur around mid-lift, although the reasoning(s) mentioned above never explicitly stated that... I don't think). That would provide a good rationale for centering the movement around the center of the valve tip I guess. Anyhow, certainly no expert here, just thinking out loud.
 
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Discussion Starter · #84 ·
I think that is why they are saying to check 90* at MID lift, because if it is set up correctly, that should be the furthest OUT from center that it will be, and should head back toward center as it continues the arc.
 

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Discussion Starter · #85 ·
Driver side looks the same as the passenger side after .040 removed.

So now I either stay with it like this, or try and slot the 8 pedestal mounting holes. The machine shop here said he doesn't have something to mount them in the make a precision slot. He said he'd die grinder the holes, so I think I'm just staying as is. Otherwise I fear I'm going to introduce too much variable in mounting these, and I will be chasing my tail, loosening one end and checking wear patterns and then going to the other end and doing the same, going back and forth trying to "nudge" the pedestals .010" at a time, back and forth.

Thoughts on THAT procedure? 🤐🤐🤐
 

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Unless you are prepared to pin the stands in place once the holes are slotted, don't bother. They will move if you slot them.

I'm always overthinking stuff, but I think you are good where you're at. The ultimate goal you are trying to accomplish is minimize side loading on the valve. That means minimizing movement out and in. That's what the mid lift (rocker 90 degree at mid lift) method should accomplish. Minimizing the swept area in the marking on the stem is showing the same thing.

Think really hard about what moving those marks ~.040" to the middle of the stem is going to do? You'll still have the same sweep in and out, so side loading is the same. You could make a case that is minimizes buckling load on the valve when it's opening against pressure (ie exhaust valve). But that's grasping at straws since you're so close to center anyway.

My thought is: Don't spend more time trying to move the rockers .040" just fix something that isn't a really a problem to begin with. By slotting the rocker holes you're going to introduce a whole new potential problem in the rocker pedestal shifting. If you had put stock rockers on you would have much more side loading and would never have checked this and wouldn't be worrying about it at all. You are far better off than that already.

Someone once told me everything in an engine is a compromise. You can change something trying to make it perfect, but in turn you alter something else. Like line honing a main to get perfect size just to shorten the crank to cam distance and introduce timing chain slack. Weight the benefits vs the downside on all this stuff.
 

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Just thinking from the point of view of minimizing angular forces on the valve stem. Why is it important to have the rocker perpendicular to the valve stem at the beginning and the end of the movement? I would think that it would be best for the rocker tip to be at the center of the valve stem when the forces are the greatest. Which at first I thought would be at max lift when the spring pressures are the greatest. However, the more I think about it, the inertial forces are probably the highest when the cam lobe is at it's steepest angle and the valvetrain is accelerating at the highest rate (which may likely occur around mid-lift, although the reasoning(s) mentioned above never explicitly stated that... I don't think). That would provide a good rationale for centering the movement around the center of the valve tip I guess. Anyhow, certainly no expert here, just thinking out loud.
Driver side looks the same as the passenger side after .040 removed.

So now I either stay with it like this, or try and slot the 8 pedestal mounting holes. The machine shop here said he doesn't have something to mount them in the make a precision slot. He said he'd die grinder the holes, so I think I'm just staying as is. Otherwise I fear I'm going to introduce too much variable in mounting these, and I will be chasing my tail, loosening one end and checking wear patterns and then going to the other end and doing the same, going back and forth trying to "nudge" the pedestals .010" at a time, back and forth.

Thoughts on THAT procedure? 🤐🤐🤐
First, so that we don't lose sight of our priorities:
Achieving 'Mid-Lift Geometry' is our goal!

Then if the rocker arm sweep can be kept minimal / thin line,
within the 'Center' of valve stem, the valve will be being
pushed downward, not sideways, thereby minimizing
geometric losses.

This helps everything, particularly achieving full valve lift.

Cheers
 

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Unless you are prepared to pin the stands in place once the holes are slotted, don't bother. They will move if you slot them.

I'm always overthinking stuff, but I think you are good where you're at. The ultimate goal you are trying to accomplish is minimize side loading on the valve. That means minimizing movement out and in. That's what the mid lift (rocker 90 degree at mid lift) method should accomplish. Minimizing the swept area in the marking on the stem is showing the same thing.

Think really hard about what moving those marks ~.040" to the middle of the stem is going to do? You'll still have the same sweep in and out, so side loading is the same. You could make a case that is minimizes buckling load on the valve when it's opening against pressure (ie exhaust valve). But that's grasping at straws since you're so close to center anyway.

My thought is: Don't spend more time trying to move the rockers .040" just fix something that isn't a really a problem to begin with. By slotting the rocker holes you're going to introduce a whole new potential problem in the rocker pedestal shifting. If you had put stock rockers on you would have much more side loading and would never have checked this and wouldn't be worrying about it at all. You are far better off than that already.

Someone once told me everything in an engine is a compromise. You can change something trying to make it perfect, but in turn you alter something else. Like line honing a main to get perfect size just to shorten the crank to cam distance and introduce timing chain slack. Weight the benefits vs the downside on all this stuff.
All good info Mike..:)

The 'Only' reason to move the rocker arm stands is 'If' you have
an acceptable sweep, 'And' you 'Also' have proper mid-lift geometry,
'But' the rocker arms are still not centered over the valve stem.

Moving the stands, as you pointed out is not easy.

This is exactly why I stated that if that was required,
he must talk to Don about doing that.

Cheers
 

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View attachment 153563 View attachment 153564 View attachment 153565
Here is the geometry at midlift. It's a pain in the butt to try and get pictures. It DOES roll to the outside, then come back as it should. I dropped the 2nd pedestal off to get .042 taken off IT, then check 1,3,5 & 7. I asked the guy doing the machining if he had a way to mount them up to slot the pedestal mounting holes, and he said maybe, but he would just run them as they were and didn't think the pattern was too bad. He said he likes it kn the exhaust side, rather than the INTAKE side because he said it would be worse on the guides if it was pushing from the intake side.

I'll run back in to town when he calls me, and see what the driver side set looks like all bolted up, and then see if I need to pursue slotting the holes.

The wear pattern starts EXACTLY in the center of the valve stem. I guess I'd have to measure the wear marks widths and average them, and then slot the holes that much? I haven't really sat and looked to figure that out. It DOES seem like my thought a few weeks ago, that if I would have slotted the holes to mount the pedestals as they plopped in the head, INSTEAD of milling out clearance for the valve cover mounting, it would almost be perfect on the valve stem. 🙄
Am I missing something?
I am not seeing sweep marks on valve stems, and I am not seeing pictures that show me proper 'Mid-Lift' yet.
 

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Discussion Starter · #90 ·
I can't take pictures of the dang rocker arms set down in the dang head very well.

My dry erase marker hasn't been working too hot either. I think it's too humid back here.
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In order, that's 3, 3, and 5. They weren't changing at all from the other side, so I just put everything away. Maybe I need to get some layout dye.
 

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Yes, using something a little darker on the valve stem would help,
but I think we can all see what the sweep pattern is now.

If you want to do something better, or more defined that's okay with me..lol

However, the most important thing to do now (in my opinion) is to verify 'Mid-Lift'.

----------------------------------------------------------------------------------

Finally, to put another perspective on the width of the sweep, let's now include the following info:

The width of the sweep pattern should not exceed 10% of the valve lift.

As an example; if the sweep patterns width amounts to say 12% of
valve lift, in my opinion you have moved into the area where your
giving up performance.

Ideally, the sweep pattern should be divided equally
between both sides of the valve stems centerline.

And the sweep pattern should not deviate more than 10%
off center of the valve stems tip.


Finally; the correct pushrod length will be determined by all of the
above, as well as the pushrods required length regarding the push
rod cup / adjuster.

-as an example-
If you must screw the adjuster all of the way down, you have changed the geometry.

---------------------------------------------------------------------

As I have stated many times before: Achieving Mid-Lift geometry is
the primary goal. The correct sweep width should come once the
proper Mid-Lift geometry is met.

All of the above contributes to determining the 'proper' length of the pushrod.

Now, while some on this forum will think I am going overboard. . Yet once again..lol.

I am simply writing about how to find the ideal geometry, which will
then determine what the proper length of the pushrod should be.

If anyone reading this info feels they can do with less, who am I to
argue with them. . But they cannot debate what is correct, or ideal!

Cheers
 
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Discussion Starter · #92 ·
Gotcha Bruce. AGAIN, I appreciate you lending your help.

I just need to find a way to check it, stuck down in the head. In the one video he used a straight edge on the retainer. I'm not sure these have a good enough spot to sit a straight edge. I will sit and look at it for a little while tonight and see what my brain can come up with.

I'd REALLY like to get this thing running soon.
 

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Gotcha Bruce. AGAIN, I appreciate you lending your help.

I just need to find a way to check it, stuck down in the head. In the one video he used a straight edge on the retainer. I'm not sure these have a good enough spot to sit a straight edge. I will sit and look at it for a little while tonight and see what my brain can come up with.

I'd REALLY like to get this thing running soon.
Installing shaft mounted rocker arms correctly is not always easy.
One must remain determined!

You have come a long way and I am sure you will overcome
all of the associated problems . .;)

Then on your next build we can install a cam with about a 0.950"
valve lift, which will require a valve with a longer stem, maybe also
requiring a lash cap, and you can step into real 'Deep Shit'..lol
 

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Discussion Starter · #94 ·
Ok, here is 2,4,6&8. Still trying to figure out how to get something down in the head to check for 90* geometry.
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So everything is looking better now except for one of the valves in the second picture.

However, that could just be it a poor picture? Some of the sweep patterns might be considered a little wide, as well as offset from the center of the valve a bit too much by some. But as I stated before things are looking much better now.

Generally speaking, the width of the sweep pattern across the valve stem is a derivative of mid-lift geometry. But mid-lift geometry must now be verified. If the mid lift geometry has to be improved just a bit, then the sweep patterns theoretically should improve also.

Where the sweep patterns are right now, I would not consider speaking to Don about modifying the pedestals.
 

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Discussion Starter · #96 ·
Ok, here's my take on checking midlift 90* geometry.

I little wall tv mount level, and some more Milwaukee blue marker and a snap ring pliers and a 90* corner bracket.

I took the rocker arm apart and made a line from center to center as best I could. I set the level on top of a valve stem and rotated the engine until it was level. Then rotated to midlift and then stuck the level on a small corner bracket and lined it up on the rocker arm line a made. Looks good enough for me to say I'm moving on. I hope it passes muster with Bruce.

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If it is off, it is not by very much at all.
 

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Ok, here's my take on checking midlift 90* geometry.

I little wall tv mount level, and some more Milwaukee blue marker and a snap ring pliers and a 90* corner bracket.

I took the rocker arm apart and made a line from center to center as best I could. I set the level on top of a valve stem and rotated the engine until it was level. Then rotated to midlift and then stuck the level on a small corner bracket and lined it up on the rocker arm line a made. Looks good enough for me to say I'm moving on. I hope it passes muster with Bruce.

View attachment 153592



If it is off, it is not by very much at all.
Well, that's a novel way to check for mid-lift, but then that is what Hot Rodding is about..lol

I am going to have to trust that at mid-lift, your line passes through the center of the rocker arm roller, as well as the center of the rocker arm trunnion bearing horizontally @ 90°, as per the drawing below.

I have left one picture above which shows the sweep pattern on that single valve stem.

Does that sweep pattern represent what you have found on the other valve stems?

Triangle Rectangle Slope Schematic Font
 

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Discussion Starter · #98 ·
It DOES travel from the intake side to the exhaust side and return to the intake side. The travel patterns pretty much look like the one in the picture. The last 2 times I've tried to get it to roll off, it hasn't cooperated. All my previous red marks were dry erase marker, so I tried the blue Milwaukee Sharpie. It doesn't seem to work much better now. I think the valve tips are getting tired of this too. 🤔
 

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It DOES travel from the intake side to the exhaust side and return to the intake side. The travel patterns pretty much look like the one in the picture. The last 2 times I've tried to get it to roll off, it hasn't cooperated. All my previous red marks were dry erase marker, so I tried the blue Milwaukee Sharpie. It doesn't seem to work much better now. I think the valve tips are getting tired of this too. 🤔
More work could be done on this, but…
If the sweep pattern on all of the valves, look as good as the one valve that I referenced in your earlier post.

And if the intersect line between the rocker arm roller tip and the rocker arm trunnion is horizontal and is at 90° at mid lift as I indicated above, then for this project I believe you’re ready to go.

Now, how are you going to order the correct pushrod length?

I’ll give you a clue…
It has to do with how far down Crower says you can move that
adjuster, without negatively impacting the geometry.

Good luck!
 
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